diff --git a/types/fs-extra-promise/fs-extra-promise-tests.ts b/types/fs-extra-promise/fs-extra-promise-tests.ts
index 1d511497a6..07fbba908b 100644
--- a/types/fs-extra-promise/fs-extra-promise-tests.ts
+++ b/types/fs-extra-promise/fs-extra-promise-tests.ts
@@ -19,7 +19,7 @@ let strOrBuf: string | Buffer;
 let buffer: Buffer;
 declare const modeNum: number;
 declare const modeStr: string;
-declare const encoding: string;
+declare const encoding: BufferEncoding;
 declare const symlinkType: "file" | "dir" | "junction";
 declare const flags: string;
 declare const srcpath: string;
@@ -195,14 +195,14 @@ bool = fs.existsSync(path);
 readStream = fs.createReadStream(path);
 readStream = fs.createReadStream(path, {
 	flags: str,
-	encoding: str,
+	encoding: str as BufferEncoding,
 	fd: num,
 	mode: num
 });
 writeStream = fs.createWriteStream(path);
 writeStream = fs.createWriteStream(path, {
 	flags: str,
-	encoding: str
+	encoding: str as BufferEncoding
 });
 
 function isDirectoryCallback(err: Error, isDirectory: boolean) {}
diff --git a/types/fs-extra/v4/index.d.ts b/types/fs-extra/v4/index.d.ts
index 14eb821103..aa5e38215c 100644
--- a/types/fs-extra/v4/index.d.ts
+++ b/types/fs-extra/v4/index.d.ts
@@ -280,12 +280,12 @@ export interface ReadOptions {
     throws?: boolean;
     fs?: object;
     reviver?: any;
-    encoding?: string;
+    encoding?: BufferEncoding;
     flag?: string;
 }
 
 export interface WriteFileOptions {
-    encoding?: string;
+    encoding?: BufferEncoding;
     flag?: string;
     mode?: number;
 }
diff --git a/types/node-expat/index.d.ts b/types/node-expat/index.d.ts
index f89ea53959..846ec9fa58 100644
--- a/types/node-expat/index.d.ts
+++ b/types/node-expat/index.d.ts
@@ -22,7 +22,7 @@ export class Parser extends Stream {
 
     parse(buf: Buffer | string, isFinal?: boolean): boolean;
 
-    setEncoding(encoding: string): void;
+    setEncoding(encoding: BufferEncoding): void;
 
     setUnknownEncoding(map: number[], convert?: string): void;
 
@@ -40,7 +40,7 @@ export class Parser extends Stream {
 
     end(cb?: () => void): void;
     end(chunk: any, cb?: () => void): void;
-    end(chunk: any, encoding: string, cb?: () => void): void;
+    end(chunk: any, encoding: BufferEncoding, cb?: () => void): void;
 
     reset(): void;
 
diff --git a/types/node-notifier/node-notifier-tests.ts b/types/node-notifier/node-notifier-tests.ts
index e7ba204dbd..870510f403 100644
--- a/types/node-notifier/node-notifier-tests.ts
+++ b/types/node-notifier/node-notifier-tests.ts
@@ -117,7 +117,7 @@ const notifier4 = new notifier.Growl({
 notifier4.notify({
     title: 'Foo',
     message: 'Hello World',
-    icon: fs.readFileSync(__dirname + '/coulson.jpg', 'r'),
+    icon: fs.readFileSync(__dirname + '/coulson.jpg', 'utf8'),
     wait: false, // if wait for user interaction
 
     // and other growl options like sticky etc.
diff --git a/types/node/child_process.d.ts b/types/node/child_process.d.ts
index 1cb3f87378..4c35028321 100644
--- a/types/node/child_process.d.ts
+++ b/types/node/child_process.d.ts
@@ -1,4 +1,5 @@
 declare module "child_process" {
+    import { BaseEncodingOptions } from 'fs';
     import * as events from "events";
     import * as net from "net";
     import { Writable, Readable, Stream, Pipe } from "stream";
@@ -268,7 +269,7 @@ declare module "child_process" {
     }
 
     interface ExecOptionsWithBufferEncoding extends ExecOptions {
-        encoding: string | null; // specify `null`.
+        encoding: BufferEncoding | null; // specify `null`.
     }
 
     interface ExecException extends Error {
@@ -289,7 +290,11 @@ declare module "child_process" {
 
     // `options` with an `encoding` whose type is `string` means stdout/stderr could either be `Buffer` or `string`.
     // There is no guarantee the `encoding` is unknown as `string` is a superset of `BufferEncoding`.
-    function exec(command: string, options: { encoding: string } & ExecOptions, callback?: (error: ExecException | null, stdout: string | Buffer, stderr: string | Buffer) => void): ChildProcess;
+    function exec(
+        command: string,
+        options: { encoding: BufferEncoding } & ExecOptions,
+        callback?: (error: ExecException | null, stdout: string | Buffer, stderr: string | Buffer) => void,
+    ): ChildProcess;
 
     // `options` without an `encoding` means stdout/stderr are definitely `string`.
     function exec(command: string, options: ExecOptions, callback?: (error: ExecException | null, stdout: string, stderr: string) => void): ChildProcess;
@@ -297,7 +302,7 @@ declare module "child_process" {
     // fallback if nothing else matches. Worst case is always `string | Buffer`.
     function exec(
         command: string,
-        options: ({ encoding?: string | null } & ExecOptions) | undefined | null,
+        options: (BaseEncodingOptions & ExecOptions) | undefined | null,
         callback?: (error: ExecException | null, stdout: string | Buffer, stderr: string | Buffer) => void,
     ): ChildProcess;
 
@@ -311,7 +316,7 @@ declare module "child_process" {
         function __promisify__(command: string, options: { encoding: "buffer" | null } & ExecOptions): PromiseWithChild<{ stdout: Buffer, stderr: Buffer }>;
         function __promisify__(command: string, options: { encoding: BufferEncoding } & ExecOptions): PromiseWithChild<{ stdout: string, stderr: string }>;
         function __promisify__(command: string, options: ExecOptions): PromiseWithChild<{ stdout: string, stderr: string }>;
-        function __promisify__(command: string, options?: ({ encoding?: string | null } & ExecOptions) | null): PromiseWithChild<{ stdout: string | Buffer, stderr: string | Buffer }>;
+        function __promisify__(command: string, options?: (BaseEncodingOptions & ExecOptions) | null): PromiseWithChild<{ stdout: string | Buffer, stderr: string | Buffer }>;
     }
 
     interface ExecFileOptions extends CommonOptions {
@@ -327,13 +332,13 @@ declare module "child_process" {
         encoding: 'buffer' | null;
     }
     interface ExecFileOptionsWithOtherEncoding extends ExecFileOptions {
-        encoding: string;
+        encoding: BufferEncoding;
     }
 
     function execFile(file: string): ChildProcess;
-    function execFile(file: string, options: ({ encoding?: string | null } & ExecFileOptions) | undefined | null): ChildProcess;
+    function execFile(file: string, options: (BaseEncodingOptions & ExecFileOptions) | undefined | null): ChildProcess;
     function execFile(file: string, args?: ReadonlyArray<string> | null): ChildProcess;
-    function execFile(file: string, args: ReadonlyArray<string> | undefined | null, options: ({ encoding?: string | null } & ExecFileOptions) | undefined | null): ChildProcess;
+    function execFile(file: string, args: ReadonlyArray<string> | undefined | null, options: (BaseEncodingOptions & ExecFileOptions) | undefined | null): ChildProcess;
 
     // no `options` definitely means stdout/stderr are `string`.
     function execFile(file: string, callback: (error: ExecException | null, stdout: string, stderr: string) => void): ChildProcess;
@@ -383,13 +388,13 @@ declare module "child_process" {
     // fallback if nothing else matches. Worst case is always `string | Buffer`.
     function execFile(
         file: string,
-        options: ({ encoding?: string | null } & ExecFileOptions) | undefined | null,
+        options: (BaseEncodingOptions & ExecFileOptions) | undefined | null,
         callback: ((error: ExecException | null, stdout: string | Buffer, stderr: string | Buffer) => void) | undefined | null,
     ): ChildProcess;
     function execFile(
         file: string,
         args: ReadonlyArray<string> | undefined | null,
-        options: ({ encoding?: string | null } & ExecFileOptions) | undefined | null,
+        options: (BaseEncodingOptions & ExecFileOptions) | undefined | null,
         callback: ((error: ExecException | null, stdout: string | Buffer, stderr: string | Buffer) => void) | undefined | null,
     ): ChildProcess;
 
@@ -405,11 +410,11 @@ declare module "child_process" {
         function __promisify__(file: string, args: string[] | undefined | null, options: ExecFileOptionsWithOtherEncoding): PromiseWithChild<{ stdout: string | Buffer, stderr: string | Buffer }>;
         function __promisify__(file: string, options: ExecFileOptions): PromiseWithChild<{ stdout: string, stderr: string }>;
         function __promisify__(file: string, args: string[] | undefined | null, options: ExecFileOptions): PromiseWithChild<{ stdout: string, stderr: string }>;
-        function __promisify__(file: string, options: ({ encoding?: string | null } & ExecFileOptions) | undefined | null): PromiseWithChild<{ stdout: string | Buffer, stderr: string | Buffer }>;
+        function __promisify__(file: string, options: (BaseEncodingOptions & ExecFileOptions) | undefined | null): PromiseWithChild<{ stdout: string | Buffer, stderr: string | Buffer }>;
         function __promisify__(
             file: string,
             args: string[] | undefined | null,
-            options: ({ encoding?: string | null } & ExecFileOptions) | undefined | null,
+            options: (BaseEncodingOptions & ExecFileOptions) | undefined | null,
         ): PromiseWithChild<{ stdout: string | Buffer, stderr: string | Buffer }>;
     }
 
@@ -427,13 +432,13 @@ declare module "child_process" {
         input?: string | NodeJS.ArrayBufferView;
         killSignal?: NodeJS.Signals | number;
         maxBuffer?: number;
-        encoding?: string;
+        encoding?: BufferEncoding;
     }
     interface SpawnSyncOptionsWithStringEncoding extends SpawnSyncOptions {
         encoding: BufferEncoding;
     }
     interface SpawnSyncOptionsWithBufferEncoding extends SpawnSyncOptions {
-        encoding: string; // specify `null`.
+        encoding: BufferEncoding; // specify `null`.
     }
     interface SpawnSyncReturns<T> {
         pid: number;
@@ -458,13 +463,13 @@ declare module "child_process" {
         shell?: string;
         killSignal?: NodeJS.Signals | number;
         maxBuffer?: number;
-        encoding?: string;
+        encoding?: BufferEncoding;
     }
     interface ExecSyncOptionsWithStringEncoding extends ExecSyncOptions {
         encoding: BufferEncoding;
     }
     interface ExecSyncOptionsWithBufferEncoding extends ExecSyncOptions {
-        encoding: string; // specify `null`.
+        encoding: BufferEncoding; // specify `null`.
     }
     function execSync(command: string): Buffer;
     function execSync(command: string, options?: ExecSyncOptionsWithStringEncoding): string;
@@ -476,14 +481,14 @@ declare module "child_process" {
         stdio?: StdioOptions;
         killSignal?: NodeJS.Signals | number;
         maxBuffer?: number;
-        encoding?: string;
+        encoding?: BufferEncoding;
         shell?: boolean | string;
     }
     interface ExecFileSyncOptionsWithStringEncoding extends ExecFileSyncOptions {
         encoding: BufferEncoding;
     }
     interface ExecFileSyncOptionsWithBufferEncoding extends ExecFileSyncOptions {
-        encoding: string; // specify `null`.
+        encoding: BufferEncoding; // specify `null`.
     }
     function execFileSync(command: string): Buffer;
     function execFileSync(command: string, options?: ExecFileSyncOptionsWithStringEncoding): string;
diff --git a/types/node/crypto.d.ts b/types/node/crypto.d.ts
index ca7b006565..3238dcab7a 100644
--- a/types/node/crypto.d.ts
+++ b/types/node/crypto.d.ts
@@ -208,7 +208,7 @@ declare module "crypto" {
         update(data: NodeJS.ArrayBufferView, input_encoding: undefined, output_encoding: HexBase64BinaryEncoding): string;
         update(data: string, input_encoding: Utf8AsciiBinaryEncoding | undefined, output_encoding: HexBase64BinaryEncoding): string;
         final(): Buffer;
-        final(output_encoding: string): string;
+        final(output_encoding: BufferEncoding): string;
         setAutoPadding(auto_padding?: boolean): this;
         // getAuthTag(): Buffer;
         // setAAD(buffer: Buffer): this; // docs only say buffer
@@ -249,7 +249,7 @@ declare module "crypto" {
         update(data: NodeJS.ArrayBufferView, input_encoding: HexBase64BinaryEncoding | undefined, output_encoding: Utf8AsciiBinaryEncoding): string;
         update(data: string, input_encoding: HexBase64BinaryEncoding | undefined, output_encoding: Utf8AsciiBinaryEncoding): string;
         final(): Buffer;
-        final(output_encoding: string): string;
+        final(output_encoding: BufferEncoding): string;
         setAutoPadding(auto_padding?: boolean): this;
         // setAuthTag(tag: NodeJS.ArrayBufferView): this;
         // setAAD(buffer: NodeJS.ArrayBufferView): this;
@@ -337,9 +337,9 @@ declare module "crypto" {
         getPrivateKey(): Buffer;
         getPrivateKey(encoding: HexBase64Latin1Encoding): string;
         setPublicKey(public_key: NodeJS.ArrayBufferView): void;
-        setPublicKey(public_key: string, encoding: string): void;
+        setPublicKey(public_key: string, encoding: BufferEncoding): void;
         setPrivateKey(private_key: NodeJS.ArrayBufferView): void;
-        setPrivateKey(private_key: string, encoding: string): void;
+        setPrivateKey(private_key: string, encoding: BufferEncoding): void;
         verifyError: number;
     }
     function getDiffieHellman(group_name: string): DiffieHellman;
@@ -429,7 +429,7 @@ declare module "crypto" {
     function createECDH(curve_name: string): ECDH;
     function timingSafeEqual(a: NodeJS.ArrayBufferView, b: NodeJS.ArrayBufferView): boolean;
     /** @deprecated since v10.0.0 */
-    const DEFAULT_ENCODING: string;
+    const DEFAULT_ENCODING: BufferEncoding;
 
     type KeyType = 'rsa' | 'dsa' | 'ec';
     type KeyFormat = 'pem' | 'der';
diff --git a/types/node/fs.d.ts b/types/node/fs.d.ts
index cc585d333e..508dc32962 100644
--- a/types/node/fs.d.ts
+++ b/types/node/fs.d.ts
@@ -2,8 +2,9 @@ declare module "fs" {
     import * as stream from "stream";
     import * as events from "events";
     import { URL } from "url";
-    export * as promises from 'fs/promises';
+    import * as promises from 'fs/promises';
 
+    export { promises };
     /**
      * Valid types for path values in "fs".
      */
@@ -11,6 +12,16 @@ declare module "fs" {
 
     export type NoParamCallback = (err: NodeJS.ErrnoException | null) => void;
 
+    export type BufferEncodingOption = 'buffer' | { encoding: 'buffer' };
+
+    export interface BaseEncodingOptions {
+        encoding?: BufferEncoding | null;
+    }
+
+    export type OpenMode = number | string;
+
+    export type Mode = number | string;
+
     export interface StatsBase<T> {
         isFile(): boolean;
         isDirectory(): boolean;
@@ -421,7 +432,7 @@ declare module "fs" {
      * @param path A path to a file. If a URL is provided, it must use the `file:` protocol.
      * @param mode A file mode. If a string is passed, it is parsed as an octal integer.
      */
-    export function chmod(path: PathLike, mode: string | number, callback: NoParamCallback): void;
+    export function chmod(path: PathLike, mode: Mode, callback: NoParamCallback): void;
 
     // NOTE: This namespace provides design-time support for util.promisify. Exported members do not exist at runtime.
     export namespace chmod {
@@ -430,7 +441,7 @@ declare module "fs" {
          * @param path A path to a file. If a URL is provided, it must use the `file:` protocol.
          * @param mode A file mode. If a string is passed, it is parsed as an octal integer.
          */
-        function __promisify__(path: PathLike, mode: string | number): Promise<void>;
+        function __promisify__(path: PathLike, mode: Mode): Promise<void>;
     }
 
     /**
@@ -438,14 +449,14 @@ declare module "fs" {
      * @param path A path to a file. If a URL is provided, it must use the `file:` protocol.
      * @param mode A file mode. If a string is passed, it is parsed as an octal integer.
      */
-    export function chmodSync(path: PathLike, mode: string | number): void;
+    export function chmodSync(path: PathLike, mode: Mode): void;
 
     /**
      * Asynchronous fchmod(2) - Change permissions of a file.
      * @param fd A file descriptor.
      * @param mode A file mode. If a string is passed, it is parsed as an octal integer.
      */
-    export function fchmod(fd: number, mode: string | number, callback: NoParamCallback): void;
+    export function fchmod(fd: number, mode: Mode, callback: NoParamCallback): void;
 
     // NOTE: This namespace provides design-time support for util.promisify. Exported members do not exist at runtime.
     export namespace fchmod {
@@ -454,7 +465,7 @@ declare module "fs" {
          * @param fd A file descriptor.
          * @param mode A file mode. If a string is passed, it is parsed as an octal integer.
          */
-        function __promisify__(fd: number, mode: string | number): Promise<void>;
+        function __promisify__(fd: number, mode: Mode): Promise<void>;
     }
 
     /**
@@ -462,14 +473,14 @@ declare module "fs" {
      * @param fd A file descriptor.
      * @param mode A file mode. If a string is passed, it is parsed as an octal integer.
      */
-    export function fchmodSync(fd: number, mode: string | number): void;
+    export function fchmodSync(fd: number, mode: Mode): void;
 
     /**
      * Asynchronous lchmod(2) - Change permissions of a file. Does not dereference symbolic links.
      * @param path A path to a file. If a URL is provided, it must use the `file:` protocol.
      * @param mode A file mode. If a string is passed, it is parsed as an octal integer.
      */
-    export function lchmod(path: PathLike, mode: string | number, callback: NoParamCallback): void;
+    export function lchmod(path: PathLike, mode: Mode, callback: NoParamCallback): void;
 
     // NOTE: This namespace provides design-time support for util.promisify. Exported members do not exist at runtime.
     export namespace lchmod {
@@ -478,7 +489,7 @@ declare module "fs" {
          * @param path A path to a file. If a URL is provided, it must use the `file:` protocol.
          * @param mode A file mode. If a string is passed, it is parsed as an octal integer.
          */
-        function __promisify__(path: PathLike, mode: string | number): Promise<void>;
+        function __promisify__(path: PathLike, mode: Mode): Promise<void>;
     }
 
     /**
@@ -486,7 +497,7 @@ declare module "fs" {
      * @param path A path to a file. If a URL is provided, it must use the `file:` protocol.
      * @param mode A file mode. If a string is passed, it is parsed as an octal integer.
      */
-    export function lchmodSync(path: PathLike, mode: string | number): void;
+    export function lchmodSync(path: PathLike, mode: Mode): void;
 
     /**
      * Asynchronous stat(2) - Get file status.
@@ -621,7 +632,7 @@ declare module "fs" {
      */
     export function readlink(
         path: PathLike,
-        options: { encoding?: BufferEncoding | null } | BufferEncoding | undefined | null,
+        options: BaseEncodingOptions | BufferEncoding | undefined | null,
         callback: (err: NodeJS.ErrnoException | null, linkString: string) => void
     ): void;
 
@@ -630,14 +641,14 @@ declare module "fs" {
      * @param path A path to a file. If a URL is provided, it must use the `file:` protocol.
      * @param options The encoding (or an object specifying the encoding), used as the encoding of the result. If not provided, `'utf8'` is used.
      */
-    export function readlink(path: PathLike, options: { encoding: "buffer" } | "buffer", callback: (err: NodeJS.ErrnoException | null, linkString: Buffer) => void): void;
+    export function readlink(path: PathLike, options: BufferEncodingOption, callback: (err: NodeJS.ErrnoException | null, linkString: Buffer) => void): void;
 
     /**
      * Asynchronous readlink(2) - read value of a symbolic link.
      * @param path A path to a file. If a URL is provided, it must use the `file:` protocol.
      * @param options The encoding (or an object specifying the encoding), used as the encoding of the result. If not provided, `'utf8'` is used.
      */
-    export function readlink(path: PathLike, options: { encoding?: string | null } | string | undefined | null, callback: (err: NodeJS.ErrnoException | null, linkString: string | Buffer) => void): void;
+    export function readlink(path: PathLike, options: BaseEncodingOptions | string | undefined | null, callback: (err: NodeJS.ErrnoException | null, linkString: string | Buffer) => void): void;
 
     /**
      * Asynchronous readlink(2) - read value of a symbolic link.
@@ -652,21 +663,21 @@ declare module "fs" {
          * @param path A path to a file. If a URL is provided, it must use the `file:` protocol.
          * @param options The encoding (or an object specifying the encoding), used as the encoding of the result. If not provided, `'utf8'` is used.
          */
-        function __promisify__(path: PathLike, options?: { encoding?: BufferEncoding | null } | BufferEncoding | null): Promise<string>;
+        function __promisify__(path: PathLike, options?: BaseEncodingOptions | BufferEncoding | null): Promise<string>;
 
         /**
          * Asynchronous readlink(2) - read value of a symbolic link.
          * @param path A path to a file. If a URL is provided, it must use the `file:` protocol.
          * @param options The encoding (or an object specifying the encoding), used as the encoding of the result. If not provided, `'utf8'` is used.
          */
-        function __promisify__(path: PathLike, options: { encoding: "buffer" } | "buffer"): Promise<Buffer>;
+        function __promisify__(path: PathLike, options: BufferEncodingOption): Promise<Buffer>;
 
         /**
          * Asynchronous readlink(2) - read value of a symbolic link.
          * @param path A path to a file. If a URL is provided, it must use the `file:` protocol.
          * @param options The encoding (or an object specifying the encoding), used as the encoding of the result. If not provided, `'utf8'` is used.
          */
-        function __promisify__(path: PathLike, options?: { encoding?: string | null } | string | null): Promise<string | Buffer>;
+        function __promisify__(path: PathLike, options?: BaseEncodingOptions | string | null): Promise<string | Buffer>;
     }
 
     /**
@@ -674,21 +685,21 @@ declare module "fs" {
      * @param path A path to a file. If a URL is provided, it must use the `file:` protocol.
      * @param options The encoding (or an object specifying the encoding), used as the encoding of the result. If not provided, `'utf8'` is used.
      */
-    export function readlinkSync(path: PathLike, options?: { encoding?: BufferEncoding | null } | BufferEncoding | null): string;
+    export function readlinkSync(path: PathLike, options?: BaseEncodingOptions | BufferEncoding | null): string;
 
     /**
      * Synchronous readlink(2) - read value of a symbolic link.
      * @param path A path to a file. If a URL is provided, it must use the `file:` protocol.
      * @param options The encoding (or an object specifying the encoding), used as the encoding of the result. If not provided, `'utf8'` is used.
      */
-    export function readlinkSync(path: PathLike, options: { encoding: "buffer" } | "buffer"): Buffer;
+    export function readlinkSync(path: PathLike, options: BufferEncodingOption): Buffer;
 
     /**
      * Synchronous readlink(2) - read value of a symbolic link.
      * @param path A path to a file. If a URL is provided, it must use the `file:` protocol.
      * @param options The encoding (or an object specifying the encoding), used as the encoding of the result. If not provided, `'utf8'` is used.
      */
-    export function readlinkSync(path: PathLike, options?: { encoding?: string | null } | string | null): string | Buffer;
+    export function readlinkSync(path: PathLike, options?: BaseEncodingOptions | string | null): string | Buffer;
 
     /**
      * Asynchronous realpath(3) - return the canonicalized absolute pathname.
@@ -697,7 +708,7 @@ declare module "fs" {
      */
     export function realpath(
         path: PathLike,
-        options: { encoding?: BufferEncoding | null } | BufferEncoding | undefined | null,
+        options: BaseEncodingOptions | BufferEncoding | undefined | null,
         callback: (err: NodeJS.ErrnoException | null, resolvedPath: string) => void
     ): void;
 
@@ -706,14 +717,14 @@ declare module "fs" {
      * @param path A path to a file. If a URL is provided, it must use the `file:` protocol.
      * @param options The encoding (or an object specifying the encoding), used as the encoding of the result. If not provided, `'utf8'` is used.
      */
-    export function realpath(path: PathLike, options: { encoding: "buffer" } | "buffer", callback: (err: NodeJS.ErrnoException | null, resolvedPath: Buffer) => void): void;
+    export function realpath(path: PathLike, options: BufferEncodingOption, callback: (err: NodeJS.ErrnoException | null, resolvedPath: Buffer) => void): void;
 
     /**
      * Asynchronous realpath(3) - return the canonicalized absolute pathname.
      * @param path A path to a file. If a URL is provided, it must use the `file:` protocol.
      * @param options The encoding (or an object specifying the encoding), used as the encoding of the result. If not provided, `'utf8'` is used.
      */
-    export function realpath(path: PathLike, options: { encoding?: string | null } | string | undefined | null, callback: (err: NodeJS.ErrnoException | null, resolvedPath: string | Buffer) => void): void;
+    export function realpath(path: PathLike, options: BaseEncodingOptions | string | undefined | null, callback: (err: NodeJS.ErrnoException | null, resolvedPath: string | Buffer) => void): void;
 
     /**
      * Asynchronous realpath(3) - return the canonicalized absolute pathname.
@@ -728,29 +739,29 @@ declare module "fs" {
          * @param path A path to a file. If a URL is provided, it must use the `file:` protocol.
          * @param options The encoding (or an object specifying the encoding), used as the encoding of the result. If not provided, `'utf8'` is used.
          */
-        function __promisify__(path: PathLike, options?: { encoding?: BufferEncoding | null } | BufferEncoding | null): Promise<string>;
+        function __promisify__(path: PathLike, options?: BaseEncodingOptions | BufferEncoding | null): Promise<string>;
 
         /**
          * Asynchronous realpath(3) - return the canonicalized absolute pathname.
          * @param path A path to a file. If a URL is provided, it must use the `file:` protocol.
          * @param options The encoding (or an object specifying the encoding), used as the encoding of the result. If not provided, `'utf8'` is used.
          */
-        function __promisify__(path: PathLike, options: { encoding: "buffer" } | "buffer"): Promise<Buffer>;
+        function __promisify__(path: PathLike, options: BufferEncodingOption): Promise<Buffer>;
 
         /**
          * Asynchronous realpath(3) - return the canonicalized absolute pathname.
          * @param path A path to a file. If a URL is provided, it must use the `file:` protocol.
          * @param options The encoding (or an object specifying the encoding), used as the encoding of the result. If not provided, `'utf8'` is used.
          */
-        function __promisify__(path: PathLike, options?: { encoding?: string | null } | string | null): Promise<string | Buffer>;
+        function __promisify__(path: PathLike, options?: BaseEncodingOptions | string | null): Promise<string | Buffer>;
 
         function native(
             path: PathLike,
-            options: { encoding?: BufferEncoding | null } | BufferEncoding | undefined | null,
+            options: BaseEncodingOptions | BufferEncoding | undefined | null,
             callback: (err: NodeJS.ErrnoException | null, resolvedPath: string) => void
         ): void;
-        function native(path: PathLike, options: { encoding: "buffer" } | "buffer", callback: (err: NodeJS.ErrnoException | null, resolvedPath: Buffer) => void): void;
-        function native(path: PathLike, options: { encoding?: string | null } | string | undefined | null, callback: (err: NodeJS.ErrnoException | null, resolvedPath: string | Buffer) => void): void;
+        function native(path: PathLike, options: BufferEncodingOption, callback: (err: NodeJS.ErrnoException | null, resolvedPath: Buffer) => void): void;
+        function native(path: PathLike, options: BaseEncodingOptions | string | undefined | null, callback: (err: NodeJS.ErrnoException | null, resolvedPath: string | Buffer) => void): void;
         function native(path: PathLike, callback: (err: NodeJS.ErrnoException | null, resolvedPath: string) => void): void;
     }
 
@@ -759,26 +770,26 @@ declare module "fs" {
      * @param path A path to a file. If a URL is provided, it must use the `file:` protocol.
      * @param options The encoding (or an object specifying the encoding), used as the encoding of the result. If not provided, `'utf8'` is used.
      */
-    export function realpathSync(path: PathLike, options?: { encoding?: BufferEncoding | null } | BufferEncoding | null): string;
+    export function realpathSync(path: PathLike, options?: BaseEncodingOptions | BufferEncoding | null): string;
 
     /**
      * Synchronous realpath(3) - return the canonicalized absolute pathname.
      * @param path A path to a file. If a URL is provided, it must use the `file:` protocol.
      * @param options The encoding (or an object specifying the encoding), used as the encoding of the result. If not provided, `'utf8'` is used.
      */
-    export function realpathSync(path: PathLike, options: { encoding: "buffer" } | "buffer"): Buffer;
+    export function realpathSync(path: PathLike, options: BufferEncodingOption): Buffer;
 
     /**
      * Synchronous realpath(3) - return the canonicalized absolute pathname.
      * @param path A path to a file. If a URL is provided, it must use the `file:` protocol.
      * @param options The encoding (or an object specifying the encoding), used as the encoding of the result. If not provided, `'utf8'` is used.
      */
-    export function realpathSync(path: PathLike, options?: { encoding?: string | null } | string | null): string | Buffer;
+    export function realpathSync(path: PathLike, options?: BaseEncodingOptions | string | null): string | Buffer;
 
     export namespace realpathSync {
-        function native(path: PathLike, options?: { encoding?: BufferEncoding | null } | BufferEncoding | null): string;
-        function native(path: PathLike, options: { encoding: "buffer" } | "buffer"): Buffer;
-        function native(path: PathLike, options?: { encoding?: string | null } | string | null): string | Buffer;
+        function native(path: PathLike, options?: BaseEncodingOptions | BufferEncoding | null): string;
+        function native(path: PathLike, options: BufferEncodingOption): Buffer;
+        function native(path: PathLike, options?: BaseEncodingOptions | string | null): string | Buffer;
     }
 
     /**
@@ -864,7 +875,7 @@ declare module "fs" {
          * A file mode. If a string is passed, it is parsed as an octal integer. If not specified
          * @default 0o777
          */
-        mode?: number | string;
+        mode?: Mode;
     }
 
     /**
@@ -881,7 +892,7 @@ declare module "fs" {
      * @param options Either the file mode, or an object optionally specifying the file mode and whether parent folders
      * should be created. If a string is passed, it is parsed as an octal integer. If not specified, defaults to `0o777`.
      */
-    export function mkdir(path: PathLike, options: number | string | (MakeDirectoryOptions & { recursive?: false; }) | null | undefined, callback: NoParamCallback): void;
+    export function mkdir(path: PathLike, options: Mode | (MakeDirectoryOptions & { recursive?: false; }) | null | undefined, callback: NoParamCallback): void;
 
     /**
      * Asynchronous mkdir(2) - create a directory.
@@ -889,7 +900,7 @@ declare module "fs" {
      * @param options Either the file mode, or an object optionally specifying the file mode and whether parent folders
      * should be created. If a string is passed, it is parsed as an octal integer. If not specified, defaults to `0o777`.
      */
-    export function mkdir(path: PathLike, options: number | string | MakeDirectoryOptions | null | undefined, callback: (err: NodeJS.ErrnoException | null, path: string | undefined) => void): void;
+    export function mkdir(path: PathLike, options: Mode | MakeDirectoryOptions | null | undefined, callback: (err: NodeJS.ErrnoException | null, path: string | undefined) => void): void;
 
     /**
      * Asynchronous mkdir(2) - create a directory with a mode of `0o777`.
@@ -913,7 +924,7 @@ declare module "fs" {
          * @param options Either the file mode, or an object optionally specifying the file mode and whether parent folders
          * should be created. If a string is passed, it is parsed as an octal integer. If not specified, defaults to `0o777`.
          */
-        function __promisify__(path: PathLike, options?: number | string | (MakeDirectoryOptions & { recursive?: false; }) | null): Promise<void>;
+        function __promisify__(path: PathLike, options?: Mode | (MakeDirectoryOptions & { recursive?: false; }) | null): Promise<void>;
 
         /**
          * Asynchronous mkdir(2) - create a directory.
@@ -921,7 +932,7 @@ declare module "fs" {
          * @param options Either the file mode, or an object optionally specifying the file mode and whether parent folders
          * should be created. If a string is passed, it is parsed as an octal integer. If not specified, defaults to `0o777`.
          */
-        function __promisify__(path: PathLike, options?: number | string | MakeDirectoryOptions | null): Promise<string | undefined>;
+        function __promisify__(path: PathLike, options?: Mode | MakeDirectoryOptions | null): Promise<string | undefined>;
     }
 
     /**
@@ -938,7 +949,7 @@ declare module "fs" {
      * @param options Either the file mode, or an object optionally specifying the file mode and whether parent folders
      * should be created. If a string is passed, it is parsed as an octal integer. If not specified, defaults to `0o777`.
      */
-    export function mkdirSync(path: PathLike, options?: number | string | (MakeDirectoryOptions & { recursive?: false; }) | null): void;
+    export function mkdirSync(path: PathLike, options?: Mode | (MakeDirectoryOptions & { recursive?: false; }) | null): void;
 
     /**
      * Synchronous mkdir(2) - create a directory.
@@ -946,14 +957,14 @@ declare module "fs" {
      * @param options Either the file mode, or an object optionally specifying the file mode and whether parent folders
      * should be created. If a string is passed, it is parsed as an octal integer. If not specified, defaults to `0o777`.
      */
-    export function mkdirSync(path: PathLike, options?: number | string | MakeDirectoryOptions | null): string | undefined;
+    export function mkdirSync(path: PathLike, options?: Mode | MakeDirectoryOptions | null): string | undefined;
 
     /**
      * Asynchronously creates a unique temporary directory.
      * Generates six random characters to be appended behind a required prefix to create a unique temporary directory.
      * @param options The encoding (or an object specifying the encoding), used as the encoding of the result. If not provided, `'utf8'` is used.
      */
-    export function mkdtemp(prefix: string, options: { encoding?: BufferEncoding | null } | BufferEncoding | undefined | null, callback: (err: NodeJS.ErrnoException | null, folder: string) => void): void;
+    export function mkdtemp(prefix: string, options: BaseEncodingOptions | BufferEncoding | undefined | null, callback: (err: NodeJS.ErrnoException | null, folder: string) => void): void;
 
     /**
      * Asynchronously creates a unique temporary directory.
@@ -967,7 +978,7 @@ declare module "fs" {
      * Generates six random characters to be appended behind a required prefix to create a unique temporary directory.
      * @param options The encoding (or an object specifying the encoding), used as the encoding of the result. If not provided, `'utf8'` is used.
      */
-    export function mkdtemp(prefix: string, options: { encoding?: string | null } | string | undefined | null, callback: (err: NodeJS.ErrnoException | null, folder: string | Buffer) => void): void;
+    export function mkdtemp(prefix: string, options: BaseEncodingOptions | string | undefined | null, callback: (err: NodeJS.ErrnoException | null, folder: string | Buffer) => void): void;
 
     /**
      * Asynchronously creates a unique temporary directory.
@@ -982,21 +993,21 @@ declare module "fs" {
          * Generates six random characters to be appended behind a required prefix to create a unique temporary directory.
          * @param options The encoding (or an object specifying the encoding), used as the encoding of the result. If not provided, `'utf8'` is used.
          */
-        function __promisify__(prefix: string, options?: { encoding?: BufferEncoding | null } | BufferEncoding | null): Promise<string>;
+        function __promisify__(prefix: string, options?: BaseEncodingOptions | BufferEncoding | null): Promise<string>;
 
         /**
          * Asynchronously creates a unique temporary directory.
          * Generates six random characters to be appended behind a required prefix to create a unique temporary directory.
          * @param options The encoding (or an object specifying the encoding), used as the encoding of the result. If not provided, `'utf8'` is used.
          */
-        function __promisify__(prefix: string, options: { encoding: "buffer" } | "buffer"): Promise<Buffer>;
+        function __promisify__(prefix: string, options: BufferEncodingOption): Promise<Buffer>;
 
         /**
          * Asynchronously creates a unique temporary directory.
          * Generates six random characters to be appended behind a required prefix to create a unique temporary directory.
          * @param options The encoding (or an object specifying the encoding), used as the encoding of the result. If not provided, `'utf8'` is used.
          */
-        function __promisify__(prefix: string, options?: { encoding?: string | null } | string | null): Promise<string | Buffer>;
+        function __promisify__(prefix: string, options?: BaseEncodingOptions | string | null): Promise<string | Buffer>;
     }
 
     /**
@@ -1004,21 +1015,21 @@ declare module "fs" {
      * Generates six random characters to be appended behind a required prefix to create a unique temporary directory.
      * @param options The encoding (or an object specifying the encoding), used as the encoding of the result. If not provided, `'utf8'` is used.
      */
-    export function mkdtempSync(prefix: string, options?: { encoding?: BufferEncoding | null } | BufferEncoding | null): string;
+    export function mkdtempSync(prefix: string, options?: BaseEncodingOptions | BufferEncoding | null): string;
 
     /**
      * Synchronously creates a unique temporary directory.
      * Generates six random characters to be appended behind a required prefix to create a unique temporary directory.
      * @param options The encoding (or an object specifying the encoding), used as the encoding of the result. If not provided, `'utf8'` is used.
      */
-    export function mkdtempSync(prefix: string, options: { encoding: "buffer" } | "buffer"): Buffer;
+    export function mkdtempSync(prefix: string, options: BufferEncodingOption): Buffer;
 
     /**
      * Synchronously creates a unique temporary directory.
      * Generates six random characters to be appended behind a required prefix to create a unique temporary directory.
      * @param options The encoding (or an object specifying the encoding), used as the encoding of the result. If not provided, `'utf8'` is used.
      */
-    export function mkdtempSync(prefix: string, options?: { encoding?: string | null } | string | null): string | Buffer;
+    export function mkdtempSync(prefix: string, options?: BaseEncodingOptions | string | null): string | Buffer;
 
     /**
      * Asynchronous readdir(3) - read a directory.
@@ -1045,7 +1056,7 @@ declare module "fs" {
      */
     export function readdir(
         path: PathLike,
-        options: { encoding?: string | null; withFileTypes?: false } | string | undefined | null,
+        options: BaseEncodingOptions & { withFileTypes?: false } | BufferEncoding | undefined | null,
         callback: (err: NodeJS.ErrnoException | null, files: string[] | Buffer[]) => void,
     ): void;
 
@@ -1060,7 +1071,7 @@ declare module "fs" {
      * @param path A path to a file. If a URL is provided, it must use the `file:` protocol.
      * @param options If called with `withFileTypes: true` the result data will be an array of Dirent.
      */
-    export function readdir(path: PathLike, options: { encoding?: string | null; withFileTypes: true }, callback: (err: NodeJS.ErrnoException | null, files: Dirent[]) => void): void;
+    export function readdir(path: PathLike, options: BaseEncodingOptions & { withFileTypes: true }, callback: (err: NodeJS.ErrnoException | null, files: Dirent[]) => void): void;
 
     // NOTE: This namespace provides design-time support for util.promisify. Exported members do not exist at runtime.
     export namespace readdir {
@@ -1083,14 +1094,14 @@ declare module "fs" {
          * @param path A path to a file. If a URL is provided, it must use the `file:` protocol.
          * @param options The encoding (or an object specifying the encoding), used as the encoding of the result. If not provided, `'utf8'` is used.
          */
-        function __promisify__(path: PathLike, options?: { encoding?: string | null; withFileTypes?: false } | string | null): Promise<string[] | Buffer[]>;
+        function __promisify__(path: PathLike, options?: BaseEncodingOptions & { withFileTypes?: false } | BufferEncoding | null): Promise<string[] | Buffer[]>;
 
         /**
          * Asynchronous readdir(3) - read a directory.
          * @param path A path to a file. If a URL is provided, it must use the `file:` protocol.
          * @param options If called with `withFileTypes: true` the result data will be an array of Dirent
          */
-        function __promisify__(path: PathLike, options: { encoding?: string | null; withFileTypes: true }): Promise<Dirent[]>;
+        function __promisify__(path: PathLike, options: BaseEncodingOptions & { withFileTypes: true }): Promise<Dirent[]>;
     }
 
     /**
@@ -1112,14 +1123,14 @@ declare module "fs" {
      * @param path A path to a file. If a URL is provided, it must use the `file:` protocol.
      * @param options The encoding (or an object specifying the encoding), used as the encoding of the result. If not provided, `'utf8'` is used.
      */
-    export function readdirSync(path: PathLike, options?: { encoding?: string | null; withFileTypes?: false } | string | null): string[] | Buffer[];
+    export function readdirSync(path: PathLike, options?: BaseEncodingOptions & { withFileTypes?: false } | BufferEncoding | null): string[] | Buffer[];
 
     /**
      * Synchronous readdir(3) - read a directory.
      * @param path A path to a file. If a URL is provided, it must use the `file:` protocol.
      * @param options If called with `withFileTypes: true` the result data will be an array of Dirent.
      */
-    export function readdirSync(path: PathLike, options: { encoding?: string | null; withFileTypes: true }): Dirent[];
+    export function readdirSync(path: PathLike, options: BaseEncodingOptions & { withFileTypes: true }): Dirent[];
 
     /**
      * Asynchronous close(2) - close a file descriptor.
@@ -1147,13 +1158,13 @@ declare module "fs" {
      * @param path A path to a file. If a URL is provided, it must use the `file:` protocol.
      * @param mode A file mode. If a string is passed, it is parsed as an octal integer. If not supplied, defaults to `0o666`.
      */
-    export function open(path: PathLike, flags: string | number, mode: string | number | undefined | null, callback: (err: NodeJS.ErrnoException | null, fd: number) => void): void;
+    export function open(path: PathLike, flags: OpenMode, mode: Mode | undefined | null, callback: (err: NodeJS.ErrnoException | null, fd: number) => void): void;
 
     /**
      * Asynchronous open(2) - open and possibly create a file. If the file is created, its mode will be `0o666`.
      * @param path A path to a file. If a URL is provided, it must use the `file:` protocol.
      */
-    export function open(path: PathLike, flags: string | number, callback: (err: NodeJS.ErrnoException | null, fd: number) => void): void;
+    export function open(path: PathLike, flags: OpenMode, callback: (err: NodeJS.ErrnoException | null, fd: number) => void): void;
 
     // NOTE: This namespace provides design-time support for util.promisify. Exported members do not exist at runtime.
     export namespace open {
@@ -1162,7 +1173,7 @@ declare module "fs" {
          * @param path A path to a file. If a URL is provided, it must use the `file:` protocol.
          * @param mode A file mode. If a string is passed, it is parsed as an octal integer. If not supplied, defaults to `0o666`.
          */
-        function __promisify__(path: PathLike, flags: string | number, mode?: string | number | null): Promise<number>;
+        function __promisify__(path: PathLike, flags: OpenMode, mode?: Mode | null): Promise<number>;
     }
 
     /**
@@ -1170,7 +1181,7 @@ declare module "fs" {
      * @param path A path to a file. If a URL is provided, it must use the `file:` protocol.
      * @param mode A file mode. If a string is passed, it is parsed as an octal integer. If not supplied, defaults to `0o666`.
      */
-    export function openSync(path: PathLike, flags: string | number, mode?: string | number | null): number;
+    export function openSync(path: PathLike, flags: OpenMode, mode?: Mode | null): number;
 
     /**
      * Asynchronously change file timestamps of the file referenced by the supplied path.
@@ -1306,7 +1317,7 @@ declare module "fs" {
         fd: number,
         string: string,
         position: number | undefined | null,
-        encoding: string | undefined | null,
+        encoding: BufferEncoding | undefined | null,
         callback: (err: NodeJS.ErrnoException | null, written: number, str: string) => void,
     ): void;
 
@@ -1349,7 +1360,7 @@ declare module "fs" {
          * @param position The offset from the beginning of the file where this data should be written. If not supplied, defaults to the current position.
          * @param encoding The expected string encoding.
          */
-        function __promisify__(fd: number, string: string, position?: number | null, encoding?: string | null): Promise<{ bytesWritten: number, buffer: string }>;
+        function __promisify__(fd: number, string: string, position?: number | null, encoding?: BufferEncoding | null): Promise<{ bytesWritten: number, buffer: string }>;
     }
 
     /**
@@ -1368,7 +1379,7 @@ declare module "fs" {
      * @param position The offset from the beginning of the file where this data should be written. If not supplied, defaults to the current position.
      * @param encoding The expected string encoding.
      */
-    export function writeSync(fd: number, string: string, position?: number | null, encoding?: string | null): number;
+    export function writeSync(fd: number, string: string, position?: number | null, encoding?: BufferEncoding | null): number;
 
     /**
      * Asynchronously reads data from the file referenced by the supplied file descriptor.
@@ -1453,7 +1464,7 @@ declare module "fs" {
      * @param options Either the encoding for the result, or an object that contains the encoding and an optional flag.
      * If a flag is not provided, it defaults to `'r'`.
      */
-    export function readFile(path: PathLike | number, options: { encoding: string; flag?: string; } | string, callback: (err: NodeJS.ErrnoException | null, data: string) => void): void;
+    export function readFile(path: PathLike | number, options: { encoding: BufferEncoding; flag?: string; } | string, callback: (err: NodeJS.ErrnoException | null, data: string) => void): void;
 
     /**
      * Asynchronously reads the entire contents of a file.
@@ -1465,7 +1476,7 @@ declare module "fs" {
      */
     export function readFile(
         path: PathLike | number,
-        options: { encoding?: string | null; flag?: string; } | string | undefined | null,
+        options: BaseEncodingOptions & { flag?: string; } | string | undefined | null,
         callback: (err: NodeJS.ErrnoException | null, data: string | Buffer) => void,
     ): void;
 
@@ -1495,7 +1506,7 @@ declare module "fs" {
          * @param options Either the encoding for the result, or an object that contains the encoding and an optional flag.
          * If a flag is not provided, it defaults to `'r'`.
          */
-        function __promisify__(path: PathLike | number, options: { encoding: string; flag?: string; } | string): Promise<string>;
+        function __promisify__(path: PathLike | number, options: { encoding: BufferEncoding; flag?: string; } | string): Promise<string>;
 
         /**
          * Asynchronously reads the entire contents of a file.
@@ -1505,7 +1516,7 @@ declare module "fs" {
          * @param options Either the encoding for the result, or an object that contains the encoding and an optional flag.
          * If a flag is not provided, it defaults to `'r'`.
          */
-        function __promisify__(path: PathLike | number, options?: { encoding?: string | null; flag?: string; } | string | null): Promise<string | Buffer>;
+        function __promisify__(path: PathLike | number, options?: BaseEncodingOptions & { flag?: string; } | string | null): Promise<string | Buffer>;
     }
 
     /**
@@ -1525,7 +1536,7 @@ declare module "fs" {
      * @param options Either the encoding for the result, or an object that contains the encoding and an optional flag.
      * If a flag is not provided, it defaults to `'r'`.
      */
-    export function readFileSync(path: PathLike | number, options: { encoding: string; flag?: string; } | string): string;
+    export function readFileSync(path: PathLike | number, options: { encoding: BufferEncoding; flag?: string; } | BufferEncoding): string;
 
     /**
      * Synchronously reads the entire contents of a file.
@@ -1535,9 +1546,9 @@ declare module "fs" {
      * @param options Either the encoding for the result, or an object that contains the encoding and an optional flag.
      * If a flag is not provided, it defaults to `'r'`.
      */
-    export function readFileSync(path: PathLike | number, options?: { encoding?: string | null; flag?: string; } | string | null): string | Buffer;
+    export function readFileSync(path: PathLike | number, options?: BaseEncodingOptions & { flag?: string; } | BufferEncoding | null): string | Buffer;
 
-    export type WriteFileOptions = { encoding?: string | null; mode?: number | string; flag?: string; } | string | null;
+    export type WriteFileOptions = BaseEncodingOptions & { mode?: Mode; flag?: string; } | string | null;
 
     /**
      * Asynchronously writes data to a file, replacing the file if it already exists.
@@ -1703,7 +1714,7 @@ declare module "fs" {
      */
     export function watch(
         filename: PathLike,
-        options: { encoding?: string | null, persistent?: boolean, recursive?: boolean } | string | null,
+        options: { encoding?: BufferEncoding | null, persistent?: boolean, recursive?: boolean } | string | null,
         listener?: (event: string, filename: string | Buffer) => void,
     ): FSWatcher;
 
@@ -1939,7 +1950,7 @@ declare module "fs" {
      */
     export function createReadStream(path: PathLike, options?: string | {
         flags?: string;
-        encoding?: string;
+        encoding?: BufferEncoding;
         fd?: number;
         mode?: number;
         autoClose?: boolean;
@@ -1959,7 +1970,7 @@ declare module "fs" {
      */
     export function createWriteStream(path: PathLike, options?: string | {
         flags?: string;
-        encoding?: string;
+        encoding?: BufferEncoding;
         fd?: number;
         mode?: number;
         autoClose?: boolean;
diff --git a/types/node/fs/promises.d.ts b/types/node/fs/promises.d.ts
index 3b9fc37eb3..6585d5fb33 100644
--- a/types/node/fs/promises.d.ts
+++ b/types/node/fs/promises.d.ts
@@ -1,4 +1,3 @@
-
 declare module 'fs/promises' {
     import {
         Stats,
@@ -10,6 +9,10 @@ declare module 'fs/promises' {
         Dirent,
         OpenDirOptions,
         Dir,
+        BaseEncodingOptions,
+        BufferEncodingOption,
+        OpenMode,
+        Mode,
     } from 'fs';
 
     interface FileHandle {
@@ -28,7 +31,7 @@ declare module 'fs/promises' {
          * If `mode` is a string, it is parsed as an octal integer.
          * If `flag` is not supplied, the default of `'a'` is used.
          */
-        appendFile(data: string | Uint8Array, options?: { encoding?: string | null, mode?: string | number, flag?: string | number } | string | null): Promise<void>;
+        appendFile(data: string | Uint8Array, options?: BaseEncodingOptions & { mode?: Mode, flag?: OpenMode } | BufferEncoding | null): Promise<void>;
 
         /**
          * Asynchronous fchown(2) - Change ownership of a file.
@@ -39,7 +42,7 @@ declare module 'fs/promises' {
          * Asynchronous fchmod(2) - Change permissions of a file.
          * @param mode A file mode. If a string is passed, it is parsed as an octal integer.
          */
-        chmod(mode: string | number): Promise<void>;
+        chmod(mode: Mode): Promise<void>;
 
         /**
          * Asynchronous fdatasync(2) - synchronize a file's in-core state with storage device.
@@ -67,7 +70,7 @@ declare module 'fs/promises' {
          * @param options An object that may contain an optional flag.
          * If a flag is not provided, it defaults to `'r'`.
          */
-        readFile(options?: { encoding?: null, flag?: string | number } | null): Promise<Buffer>;
+        readFile(options?: { encoding?: null, flag?: OpenMode } | null): Promise<Buffer>;
 
         /**
          * Asynchronously reads the entire contents of a file. The underlying file will _not_ be closed automatically.
@@ -75,7 +78,7 @@ declare module 'fs/promises' {
          * @param options An object that may contain an optional flag.
          * If a flag is not provided, it defaults to `'r'`.
          */
-        readFile(options: { encoding: BufferEncoding, flag?: string | number } | BufferEncoding): Promise<string>;
+        readFile(options: { encoding: BufferEncoding, flag?: OpenMode } | BufferEncoding): Promise<string>;
 
         /**
          * Asynchronously reads the entire contents of a file. The underlying file will _not_ be closed automatically.
@@ -83,7 +86,7 @@ declare module 'fs/promises' {
          * @param options An object that may contain an optional flag.
          * If a flag is not provided, it defaults to `'r'`.
          */
-        readFile(options?: { encoding?: string | null, flag?: string | number } | string | null): Promise<string | Buffer>;
+        readFile(options?: BaseEncodingOptions & { flag?: OpenMode } | BufferEncoding | null): Promise<string | Buffer>;
 
         /**
          * Asynchronous fstat(2) - Get file status.
@@ -122,7 +125,7 @@ declare module 'fs/promises' {
          * @param position The offset from the beginning of the file where this data should be written. If not supplied, defaults to the current position.
          * @param encoding The expected string encoding.
          */
-        write(data: string | Uint8Array, position?: number | null, encoding?: string | null): Promise<{ bytesWritten: number, buffer: string }>;
+        write(data: string | Uint8Array, position?: number | null, encoding?: BufferEncoding | null): Promise<{ bytesWritten: number, buffer: string }>;
 
         /**
          * Asynchronously writes data to a file, replacing the file if it already exists. The underlying file will _not_ be closed automatically.
@@ -135,7 +138,7 @@ declare module 'fs/promises' {
          * If `mode` is a string, it is parsed as an octal integer.
          * If `flag` is not supplied, the default of `'w'` is used.
          */
-        writeFile(data: string | Uint8Array, options?: { encoding?: string | null, mode?: string | number, flag?: string | number } | string | null): Promise<void>;
+        writeFile(data: string | Uint8Array, options?: BaseEncodingOptions & { mode?: Mode, flag?: OpenMode } | BufferEncoding | null): Promise<void>;
 
         /**
          * See `fs.writev` promisified version.
@@ -179,7 +182,7 @@ declare module 'fs/promises' {
      * @param mode A file mode. If a string is passed, it is parsed as an octal integer. If not
      * supplied, defaults to `0o666`.
      */
-    function open(path: PathLike, flags: string | number, mode?: string | number): Promise<FileHandle>;
+    function open(path: PathLike, flags: string | number, mode?: Mode): Promise<FileHandle>;
 
     /**
      * Asynchronously reads data from the file referenced by the supplied `FileHandle`.
@@ -223,7 +226,7 @@ declare module 'fs/promises' {
      * @param position The offset from the beginning of the file where this data should be written. If not supplied, defaults to the current position.
      * @param encoding The expected string encoding.
      */
-    function write(handle: FileHandle, string: string, position?: number | null, encoding?: string | null): Promise<{ bytesWritten: number, buffer: string }>;
+    function write(handle: FileHandle, string: string, position?: number | null, encoding?: BufferEncoding | null): Promise<{ bytesWritten: number, buffer: string }>;
 
     /**
      * Asynchronous rename(2) - Change the name or location of a file or directory.
@@ -280,7 +283,7 @@ declare module 'fs/promises' {
      * @param options Either the file mode, or an object optionally specifying the file mode and whether parent folders
      * should be created. If a string is passed, it is parsed as an octal integer. If not specified, defaults to `0o777`.
      */
-    function mkdir(path: PathLike, options?: number | string | (MakeDirectoryOptions & { recursive?: false; }) | null): Promise<void>;
+    function mkdir(path: PathLike, options?: Mode | (MakeDirectoryOptions & { recursive?: false; }) | null): Promise<void>;
 
     /**
      * Asynchronous mkdir(2) - create a directory.
@@ -288,14 +291,14 @@ declare module 'fs/promises' {
      * @param options Either the file mode, or an object optionally specifying the file mode and whether parent folders
      * should be created. If a string is passed, it is parsed as an octal integer. If not specified, defaults to `0o777`.
      */
-    function mkdir(path: PathLike, options?: number | string | MakeDirectoryOptions | null): Promise<string | undefined>;
+    function mkdir(path: PathLike, options?: Mode | MakeDirectoryOptions | null): Promise<string | undefined>;
 
     /**
      * Asynchronous readdir(3) - read a directory.
      * @param path A path to a file. If a URL is provided, it must use the `file:` protocol.
      * @param options The encoding (or an object specifying the encoding), used as the encoding of the result. If not provided, `'utf8'` is used.
      */
-    function readdir(path: PathLike, options?: { encoding?: BufferEncoding | null; withFileTypes?: false } | BufferEncoding | null): Promise<string[]>;
+    function readdir(path: PathLike, options?: BaseEncodingOptions & { withFileTypes?: false } | BufferEncoding | null): Promise<string[]>;
 
     /**
      * Asynchronous readdir(3) - read a directory.
@@ -309,35 +312,35 @@ declare module 'fs/promises' {
      * @param path A path to a file. If a URL is provided, it must use the `file:` protocol.
      * @param options The encoding (or an object specifying the encoding), used as the encoding of the result. If not provided, `'utf8'` is used.
      */
-    function readdir(path: PathLike, options?: { encoding?: string | null; withFileTypes?: false } | string | null): Promise<string[] | Buffer[]>;
+    function readdir(path: PathLike, options?: BaseEncodingOptions & { withFileTypes?: false } | BufferEncoding | null): Promise<string[] | Buffer[]>;
 
     /**
      * Asynchronous readdir(3) - read a directory.
      * @param path A path to a file. If a URL is provided, it must use the `file:` protocol.
      * @param options If called with `withFileTypes: true` the result data will be an array of Dirent.
      */
-    function readdir(path: PathLike, options: { encoding?: string | null; withFileTypes: true }): Promise<Dirent[]>;
+    function readdir(path: PathLike, options: BaseEncodingOptions & { withFileTypes: true }): Promise<Dirent[]>;
 
     /**
      * Asynchronous readlink(2) - read value of a symbolic link.
      * @param path A path to a file. If a URL is provided, it must use the `file:` protocol.
      * @param options The encoding (or an object specifying the encoding), used as the encoding of the result. If not provided, `'utf8'` is used.
      */
-    function readlink(path: PathLike, options?: { encoding?: BufferEncoding | null } | BufferEncoding | null): Promise<string>;
+    function readlink(path: PathLike, options?: BaseEncodingOptions | BufferEncoding | null): Promise<string>;
 
     /**
      * Asynchronous readlink(2) - read value of a symbolic link.
      * @param path A path to a file. If a URL is provided, it must use the `file:` protocol.
      * @param options The encoding (or an object specifying the encoding), used as the encoding of the result. If not provided, `'utf8'` is used.
      */
-    function readlink(path: PathLike, options: { encoding: "buffer" } | "buffer"): Promise<Buffer>;
+    function readlink(path: PathLike, options: BufferEncodingOption): Promise<Buffer>;
 
     /**
      * Asynchronous readlink(2) - read value of a symbolic link.
      * @param path A path to a file. If a URL is provided, it must use the `file:` protocol.
      * @param options The encoding (or an object specifying the encoding), used as the encoding of the result. If not provided, `'utf8'` is used.
      */
-    function readlink(path: PathLike, options?: { encoding?: string | null } | string | null): Promise<string | Buffer>;
+    function readlink(path: PathLike, options?: BaseEncodingOptions | string | null): Promise<string | Buffer>;
 
     /**
      * Asynchronous symlink(2) - Create a new symbolic link to an existing file.
@@ -384,21 +387,21 @@ declare module 'fs/promises' {
      * @param handle A `FileHandle`.
      * @param mode A file mode. If a string is passed, it is parsed as an octal integer.
      */
-    function fchmod(handle: FileHandle, mode: string | number): Promise<void>;
+    function fchmod(handle: FileHandle, mode: Mode): Promise<void>;
 
     /**
      * Asynchronous chmod(2) - Change permissions of a file.
      * @param path A path to a file. If a URL is provided, it must use the `file:` protocol.
      * @param mode A file mode. If a string is passed, it is parsed as an octal integer.
      */
-    function chmod(path: PathLike, mode: string | number): Promise<void>;
+    function chmod(path: PathLike, mode: Mode): Promise<void>;
 
     /**
      * Asynchronous lchmod(2) - Change permissions of a file. Does not dereference symbolic links.
      * @param path A path to a file. If a URL is provided, it must use the `file:` protocol.
      * @param mode A file mode. If a string is passed, it is parsed as an octal integer.
      */
-    function lchmod(path: PathLike, mode: string | number): Promise<void>;
+    function lchmod(path: PathLike, mode: Mode): Promise<void>;
 
     /**
      * Asynchronous lchown(2) - Change ownership of a file. Does not dereference symbolic links.
@@ -439,42 +442,42 @@ declare module 'fs/promises' {
      * @param path A path to a file. If a URL is provided, it must use the `file:` protocol.
      * @param options The encoding (or an object specifying the encoding), used as the encoding of the result. If not provided, `'utf8'` is used.
      */
-    function realpath(path: PathLike, options?: { encoding?: BufferEncoding | null } | BufferEncoding | null): Promise<string>;
+    function realpath(path: PathLike, options?: BaseEncodingOptions | BufferEncoding | null): Promise<string>;
 
     /**
      * Asynchronous realpath(3) - return the canonicalized absolute pathname.
      * @param path A path to a file. If a URL is provided, it must use the `file:` protocol.
      * @param options The encoding (or an object specifying the encoding), used as the encoding of the result. If not provided, `'utf8'` is used.
      */
-    function realpath(path: PathLike, options: { encoding: "buffer" } | "buffer"): Promise<Buffer>;
+    function realpath(path: PathLike, options: BufferEncodingOption): Promise<Buffer>;
 
     /**
      * Asynchronous realpath(3) - return the canonicalized absolute pathname.
      * @param path A path to a file. If a URL is provided, it must use the `file:` protocol.
      * @param options The encoding (or an object specifying the encoding), used as the encoding of the result. If not provided, `'utf8'` is used.
      */
-    function realpath(path: PathLike, options?: { encoding?: string | null } | string | null): Promise<string | Buffer>;
+    function realpath(path: PathLike, options?: BaseEncodingOptions | BufferEncoding | null): Promise<string | Buffer>;
 
     /**
      * Asynchronously creates a unique temporary directory.
      * Generates six random characters to be appended behind a required `prefix` to create a unique temporary directory.
      * @param options The encoding (or an object specifying the encoding), used as the encoding of the result. If not provided, `'utf8'` is used.
      */
-    function mkdtemp(prefix: string, options?: { encoding?: BufferEncoding | null } | BufferEncoding | null): Promise<string>;
+    function mkdtemp(prefix: string, options?: BaseEncodingOptions | BufferEncoding | null): Promise<string>;
 
     /**
      * Asynchronously creates a unique temporary directory.
      * Generates six random characters to be appended behind a required `prefix` to create a unique temporary directory.
      * @param options The encoding (or an object specifying the encoding), used as the encoding of the result. If not provided, `'utf8'` is used.
      */
-    function mkdtemp(prefix: string, options: { encoding: "buffer" } | "buffer"): Promise<Buffer>;
+    function mkdtemp(prefix: string, options: BufferEncodingOption): Promise<Buffer>;
 
     /**
      * Asynchronously creates a unique temporary directory.
      * Generates six random characters to be appended behind a required `prefix` to create a unique temporary directory.
      * @param options The encoding (or an object specifying the encoding), used as the encoding of the result. If not provided, `'utf8'` is used.
      */
-    function mkdtemp(prefix: string, options?: { encoding?: string | null } | string | null): Promise<string | Buffer>;
+    function mkdtemp(prefix: string, options?: BaseEncodingOptions | BufferEncoding | null): Promise<string | Buffer>;
 
     /**
      * Asynchronously writes data to a file, replacing the file if it already exists.
@@ -489,7 +492,7 @@ declare module 'fs/promises' {
      * If `mode` is a string, it is parsed as an octal integer.
      * If `flag` is not supplied, the default of `'w'` is used.
      */
-    function writeFile(path: PathLike | FileHandle, data: string | Uint8Array, options?: { encoding?: string | null, mode?: string | number, flag?: string | number } | string | null): Promise<void>;
+    function writeFile(path: PathLike | FileHandle, data: string | Uint8Array, options?: BaseEncodingOptions & { mode?: Mode, flag?: OpenMode } | BufferEncoding | null): Promise<void>;
 
     /**
      * Asynchronously append data to a file, creating the file if it does not exist.
@@ -503,7 +506,7 @@ declare module 'fs/promises' {
      * If `mode` is a string, it is parsed as an octal integer.
      * If `flag` is not supplied, the default of `'a'` is used.
      */
-    function appendFile(path: PathLike | FileHandle, data: string | Uint8Array, options?: { encoding?: string | null, mode?: string | number, flag?: string | number } | string | null): Promise<void>;
+    function appendFile(path: PathLike | FileHandle, data: string | Uint8Array, options?: BaseEncodingOptions & { mode?: Mode, flag?: OpenMode } | BufferEncoding | null): Promise<void>;
 
     /**
      * Asynchronously reads the entire contents of a file.
@@ -512,7 +515,7 @@ declare module 'fs/promises' {
      * @param options An object that may contain an optional flag.
      * If a flag is not provided, it defaults to `'r'`.
      */
-    function readFile(path: PathLike | FileHandle, options?: { encoding?: null, flag?: string | number } | null): Promise<Buffer>;
+    function readFile(path: PathLike | FileHandle, options?: { encoding?: null, flag?: OpenMode } | null): Promise<Buffer>;
 
     /**
      * Asynchronously reads the entire contents of a file.
@@ -521,7 +524,7 @@ declare module 'fs/promises' {
      * @param options An object that may contain an optional flag.
      * If a flag is not provided, it defaults to `'r'`.
      */
-    function readFile(path: PathLike | FileHandle, options: { encoding: BufferEncoding, flag?: string | number } | BufferEncoding): Promise<string>;
+    function readFile(path: PathLike | FileHandle, options: { encoding: BufferEncoding, flag?: OpenMode } | BufferEncoding): Promise<string>;
 
     /**
      * Asynchronously reads the entire contents of a file.
@@ -530,7 +533,7 @@ declare module 'fs/promises' {
      * @param options An object that may contain an optional flag.
      * If a flag is not provided, it defaults to `'r'`.
      */
-    function readFile(path: PathLike | FileHandle, options?: { encoding?: string | null, flag?: string | number } | string | null): Promise<string | Buffer>;
+    function readFile(path: PathLike | FileHandle, options?: BaseEncodingOptions & { flag?: OpenMode } | BufferEncoding | null): Promise<string | Buffer>;
 
     function opendir(path: string, options?: OpenDirOptions): Promise<Dir>;
 }
diff --git a/types/node/globals.d.ts b/types/node/globals.d.ts
index 24356649ef..0711d25804 100644
--- a/types/node/globals.d.ts
+++ b/types/node/globals.d.ts
@@ -327,7 +327,7 @@ declare class Buffer extends Uint8Array {
     write(string: string, encoding?: BufferEncoding): number;
     write(string: string, offset: number, encoding?: BufferEncoding): number;
     write(string: string, offset: number, length: number, encoding?: BufferEncoding): number;
-    toString(encoding?: string, start?: number, end?: number): string;
+    toString(encoding?: BufferEncoding, start?: number, end?: number): string;
     toJSON(): { type: 'Buffer'; data: number[] };
     equals(otherBuffer: Uint8Array): boolean;
     compare(
@@ -572,7 +572,7 @@ declare namespace NodeJS {
     interface ReadableStream extends EventEmitter {
         readable: boolean;
         read(size?: number): string | Buffer;
-        setEncoding(encoding: string): this;
+        setEncoding(encoding: BufferEncoding): this;
         pause(): this;
         resume(): this;
         isPaused(): boolean;
@@ -586,10 +586,10 @@ declare namespace NodeJS {
     interface WritableStream extends EventEmitter {
         writable: boolean;
         write(buffer: Uint8Array | string, cb?: (err?: Error | null) => void): boolean;
-        write(str: string, encoding?: string, cb?: (err?: Error | null) => void): boolean;
+        write(str: string, encoding?: BufferEncoding, cb?: (err?: Error | null) => void): boolean;
         end(cb?: () => void): void;
         end(data: string | Uint8Array, cb?: () => void): void;
-        end(str: string, encoding?: string, cb?: () => void): void;
+        end(str: string, encoding?: BufferEncoding, cb?: () => void): void;
     }
 
     interface ReadWriteStream extends ReadableStream, WritableStream { }
diff --git a/types/node/http2.d.ts b/types/node/http2.d.ts
index 667dc1c01c..c411b2d0c6 100644
--- a/types/node/http2.d.ts
+++ b/types/node/http2.d.ts
@@ -652,7 +652,7 @@ declare module "http2" {
         addTrailers(trailers: OutgoingHttpHeaders): void;
         end(callback?: () => void): void;
         end(data: string | Uint8Array, callback?: () => void): void;
-        end(data: string | Uint8Array, encoding: string, callback?: () => void): void;
+        end(data: string | Uint8Array, encoding: BufferEncoding, callback?: () => void): void;
         getHeader(name: string): string;
         getHeaderNames(): string[];
         getHeaders(): OutgoingHttpHeaders;
@@ -661,7 +661,7 @@ declare module "http2" {
         setHeader(name: string, value: number | string | string[]): void;
         setTimeout(msecs: number, callback?: () => void): void;
         write(chunk: string | Uint8Array, callback?: (err: Error) => void): boolean;
-        write(chunk: string | Uint8Array, encoding: string, callback?: (err: Error) => void): boolean;
+        write(chunk: string | Uint8Array, encoding: BufferEncoding, callback?: (err: Error) => void): boolean;
         writeContinue(): void;
         writeHead(statusCode: number, headers?: OutgoingHttpHeaders): this;
         writeHead(statusCode: number, statusMessage: string, headers?: OutgoingHttpHeaders): this;
diff --git a/types/node/inspector.d.ts b/types/node/inspector.d.ts
index b14aed2b3f..1c577346ed 100644
--- a/types/node/inspector.d.ts
+++ b/types/node/inspector.d.ts
@@ -3031,4 +3031,11 @@ declare module "inspector" {
      * Return the URL of the active inspector, or `undefined` if there is none.
      */
     function url(): string | undefined;
+
+    /**
+     * Blocks until a client (existing or connected later) has sent
+     * `Runtime.runIfWaitingForDebugger` command.
+     * An exception will be thrown if there is no active inspector.
+     */
+    function waitForDebugger(): void;
 }
diff --git a/types/node/net.d.ts b/types/node/net.d.ts
index 8eb5c7b164..c45aaa257d 100644
--- a/types/node/net.d.ts
+++ b/types/node/net.d.ts
@@ -58,14 +58,14 @@ declare module "net" {
 
         // Extended base methods
         write(buffer: Uint8Array | string, cb?: (err?: Error) => void): boolean;
-        write(str: Uint8Array | string, encoding?: string, cb?: (err?: Error) => void): boolean;
+        write(str: Uint8Array | string, encoding?: BufferEncoding, cb?: (err?: Error) => void): boolean;
 
         connect(options: SocketConnectOpts, connectionListener?: () => void): this;
         connect(port: number, host: string, connectionListener?: () => void): this;
         connect(port: number, connectionListener?: () => void): this;
         connect(path: string, connectionListener?: () => void): this;
 
-        setEncoding(encoding?: string): this;
+        setEncoding(encoding?: BufferEncoding): this;
         pause(): this;
         resume(): this;
         setTimeout(timeout: number, callback?: () => void): this;
@@ -89,7 +89,7 @@ declare module "net" {
         // Extended base methods
         end(cb?: () => void): void;
         end(buffer: Uint8Array | string, cb?: () => void): void;
-        end(str: Uint8Array | string, encoding?: string, cb?: () => void): void;
+        end(str: Uint8Array | string, encoding?: BufferEncoding, cb?: () => void): void;
 
         /**
          * events.EventEmitter
diff --git a/types/node/os.d.ts b/types/node/os.d.ts
index d98a145f85..1aadc68e22 100644
--- a/types/node/os.d.ts
+++ b/types/node/os.d.ts
@@ -49,7 +49,7 @@ declare module "os" {
     function networkInterfaces(): NodeJS.Dict<NetworkInterfaceInfo[]>;
     function homedir(): string;
     function userInfo(options: { encoding: 'buffer' }): UserInfo<Buffer>;
-    function userInfo(options?: { encoding: string }): UserInfo<string>;
+    function userInfo(options?: { encoding: BufferEncoding }): UserInfo<string>;
 
     type SignalConstants = {
         [key in NodeJS.Signals]: number;
diff --git a/types/node/scripts/generate-inspector/index.ts b/types/node/scripts/generate-inspector/index.ts
index bd51cb9da6..34e4024e3a 100644
--- a/types/node/scripts/generate-inspector/index.ts
+++ b/types/node/scripts/generate-inspector/index.ts
@@ -28,7 +28,7 @@ const httpsGet = (url: string) => new Promise<string>((resolve, reject) => {
 // Input arguments
 const tag = process.argv[2] || process.version;
 
-const V8_PROTOCOL_URL = `https://raw.githubusercontent.com/nodejs/node/${tag}/deps/v8/src/inspector/js_protocol-1.3.json`;
+const V8_PROTOCOL_URL = `https://raw.githubusercontent.com/nodejs/node/${tag}/deps/v8/include/js_protocol-1.3.json`;
 const NODE_PROTOCOL_URL = `https://raw.githubusercontent.com/nodejs/node/${tag}/src/inspector/node_protocol.pdl`;
 const INSPECTOR_PROTOCOL_REMOTE = `https://chromium.googlesource.com/deps/inspector_protocol`;
 const INSPECTOR_PROTOCOL_LOCAL_DIR = "/tmp/inspector_protocol";
diff --git a/types/node/scripts/generate-inspector/inspector.d.ts.template b/types/node/scripts/generate-inspector/inspector.d.ts.template
index b9c496bcec..77139664d5 100644
--- a/types/node/scripts/generate-inspector/inspector.d.ts.template
+++ b/types/node/scripts/generate-inspector/inspector.d.ts.template
@@ -84,5 +84,5 @@ declare module "inspector" {
      * `Runtime.runIfWaitingForDebugger` command.
      * An exception will be thrown if there is no active inspector.
      */
-    waitForDebugger();
+    function waitForDebugger(): void;
 }
diff --git a/types/node/stream.d.ts b/types/node/stream.d.ts
index de5476faf8..725d34376c 100644
--- a/types/node/stream.d.ts
+++ b/types/node/stream.d.ts
@@ -12,7 +12,7 @@ declare module "stream" {
 
         interface ReadableOptions {
             highWaterMark?: number;
-            encoding?: string;
+            encoding?: BufferEncoding;
             objectMode?: boolean;
             read?(this: Readable, size: number): void;
             destroy?(this: Readable, error: Error | null, callback: (error: Error | null) => void): void;
@@ -33,14 +33,14 @@ declare module "stream" {
             constructor(opts?: ReadableOptions);
             _read(size: number): void;
             read(size?: number): any;
-            setEncoding(encoding: string): this;
+            setEncoding(encoding: BufferEncoding): this;
             pause(): this;
             resume(): this;
             isPaused(): boolean;
             unpipe(destination?: NodeJS.WritableStream): this;
             unshift(chunk: any, encoding?: BufferEncoding): void;
             wrap(oldStream: NodeJS.ReadableStream): this;
-            push(chunk: any, encoding?: string): boolean;
+            push(chunk: any, encoding?: BufferEncoding): boolean;
             _destroy(error: Error | null, callback: (error?: Error | null) => void): void;
             destroy(error?: Error): void;
 
@@ -124,11 +124,11 @@ declare module "stream" {
         interface WritableOptions {
             highWaterMark?: number;
             decodeStrings?: boolean;
-            defaultEncoding?: string;
+            defaultencoding?: BufferEncoding;
             objectMode?: boolean;
             emitClose?: boolean;
-            write?(this: Writable, chunk: any, encoding: string, callback: (error?: Error | null) => void): void;
-            writev?(this: Writable, chunks: Array<{ chunk: any, encoding: string }>, callback: (error?: Error | null) => void): void;
+            write?(this: Writable, chunk: any, encoding: BufferEncoding, callback: (error?: Error | null) => void): void;
+            writev?(this: Writable, chunks: Array<{ chunk: any, encoding: BufferEncoding }>, callback: (error?: Error | null) => void): void;
             destroy?(this: Writable, error: Error | null, callback: (error: Error | null) => void): void;
             final?(this: Writable, callback: (error?: Error | null) => void): void;
             autoDestroy?: boolean;
@@ -144,16 +144,16 @@ declare module "stream" {
             readonly writableCorked: number;
             destroyed: boolean;
             constructor(opts?: WritableOptions);
-            _write(chunk: any, encoding: string, callback: (error?: Error | null) => void): void;
-            _writev?(chunks: Array<{ chunk: any, encoding: string }>, callback: (error?: Error | null) => void): void;
+            _write(chunk: any, encoding: BufferEncoding, callback: (error?: Error | null) => void): void;
+            _writev?(chunks: Array<{ chunk: any, encoding: BufferEncoding }>, callback: (error?: Error | null) => void): void;
             _destroy(error: Error | null, callback: (error?: Error | null) => void): void;
             _final(callback: (error?: Error | null) => void): void;
             write(chunk: any, cb?: (error: Error | null | undefined) => void): boolean;
-            write(chunk: any, encoding: string, cb?: (error: Error | null | undefined) => void): boolean;
-            setDefaultEncoding(encoding: string): this;
+            write(chunk: any, encoding: BufferEncoding, cb?: (error: Error | null | undefined) => void): boolean;
+            setDefaultEncoding(encoding: BufferEncoding): this;
             end(cb?: () => void): void;
             end(chunk: any, cb?: () => void): void;
-            end(chunk: any, encoding: string, cb?: () => void): void;
+            end(chunk: any, encoding: BufferEncoding, cb?: () => void): void;
             cork(): void;
             uncork(): void;
             destroy(error?: Error): void;
@@ -233,8 +233,8 @@ declare module "stream" {
             writableHighWaterMark?: number;
             writableCorked?: number;
             read?(this: Duplex, size: number): void;
-            write?(this: Duplex, chunk: any, encoding: string, callback: (error?: Error | null) => void): void;
-            writev?(this: Duplex, chunks: Array<{ chunk: any, encoding: string }>, callback: (error?: Error | null) => void): void;
+            write?(this: Duplex, chunk: any, encoding: BufferEncoding, callback: (error?: Error | null) => void): void;
+            writev?(this: Duplex, chunks: Array<{ chunk: any, encoding: BufferEncoding }>, callback: (error?: Error | null) => void): void;
             final?(this: Duplex, callback: (error?: Error | null) => void): void;
             destroy?(this: Duplex, error: Error | null, callback: (error: Error | null) => void): void;
         }
@@ -249,16 +249,16 @@ declare module "stream" {
             readonly writableObjectMode: boolean;
             readonly writableCorked: number;
             constructor(opts?: DuplexOptions);
-            _write(chunk: any, encoding: string, callback: (error?: Error | null) => void): void;
-            _writev?(chunks: Array<{ chunk: any, encoding: string }>, callback: (error?: Error | null) => void): void;
+            _write(chunk: any, encoding: BufferEncoding, callback: (error?: Error | null) => void): void;
+            _writev?(chunks: Array<{ chunk: any, encoding: BufferEncoding }>, callback: (error?: Error | null) => void): void;
             _destroy(error: Error | null, callback: (error: Error | null) => void): void;
             _final(callback: (error?: Error | null) => void): void;
-            write(chunk: any, encoding?: string, cb?: (error: Error | null | undefined) => void): boolean;
+            write(chunk: any, encoding?: BufferEncoding, cb?: (error: Error | null | undefined) => void): boolean;
             write(chunk: any, cb?: (error: Error | null | undefined) => void): boolean;
-            setDefaultEncoding(encoding: string): this;
+            setDefaultEncoding(encoding: BufferEncoding): this;
             end(cb?: () => void): void;
             end(chunk: any, cb?: () => void): void;
-            end(chunk: any, encoding?: string, cb?: () => void): void;
+            end(chunk: any, encoding?: BufferEncoding, cb?: () => void): void;
             cork(): void;
             uncork(): void;
         }
@@ -267,17 +267,17 @@ declare module "stream" {
 
         interface TransformOptions extends DuplexOptions {
             read?(this: Transform, size: number): void;
-            write?(this: Transform, chunk: any, encoding: string, callback: (error?: Error | null) => void): void;
-            writev?(this: Transform, chunks: Array<{ chunk: any, encoding: string }>, callback: (error?: Error | null) => void): void;
+            write?(this: Transform, chunk: any, encoding: BufferEncoding, callback: (error?: Error | null) => void): void;
+            writev?(this: Transform, chunks: Array<{ chunk: any, encoding: BufferEncoding }>, callback: (error?: Error | null) => void): void;
             final?(this: Transform, callback: (error?: Error | null) => void): void;
             destroy?(this: Transform, error: Error | null, callback: (error: Error | null) => void): void;
-            transform?(this: Transform, chunk: any, encoding: string, callback: TransformCallback): void;
+            transform?(this: Transform, chunk: any, encoding: BufferEncoding, callback: TransformCallback): void;
             flush?(this: Transform, callback: TransformCallback): void;
         }
 
         class Transform extends Duplex {
             constructor(opts?: TransformOptions);
-            _transform(chunk: any, encoding: string, callback: TransformCallback): void;
+            _transform(chunk: any, encoding: BufferEncoding, callback: TransformCallback): void;
             _flush(callback: TransformCallback): void;
         }
 
diff --git a/types/node/string_decoder.d.ts b/types/node/string_decoder.d.ts
index fe0e0b4d2d..a6a40601f0 100644
--- a/types/node/string_decoder.d.ts
+++ b/types/node/string_decoder.d.ts
@@ -1,6 +1,6 @@
 declare module "string_decoder" {
     class StringDecoder {
-        constructor(encoding?: string);
+        constructor(encoding?: BufferEncoding);
         write(buffer: Buffer): string;
         end(buffer?: Buffer): string;
     }
diff --git a/types/node/test/fs.ts b/types/node/test/fs.ts
index 024ae5fcd5..de90cd737a 100644
--- a/types/node/test/fs.ts
+++ b/types/node/test/fs.ts
@@ -34,8 +34,8 @@ import * as util from 'util';
     let content: string;
     let buffer: Buffer;
     let stringOrBuffer: string | Buffer;
-    const nullEncoding: string | null = null;
-    const stringEncoding: string | null = 'utf8';
+    const nullEncoding: BufferEncoding | null = null;
+    const stringEncoding: BufferEncoding | null = 'utf8';
 
     content = fs.readFileSync('testfile', 'utf8');
     content = fs.readFileSync('testfile', { encoding: 'utf8' });
@@ -190,7 +190,6 @@ async function testPromisify() {
     fs.readlink('/path/to/folder', { encoding: undefined }, (err, linkString) => s = linkString);
     fs.readlink('/path/to/folder', { encoding: 'utf8' }, (err, linkString) => s = linkString);
     fs.readlink('/path/to/folder', { encoding: 'buffer' }, (err, linkString) => b = linkString);
-    fs.readlink('/path/to/folder', { encoding: s }, (err, linkString) => typeof linkString === "string" ? s = linkString : b = linkString);
 
     s = fs.readlinkSync('/path/to/folder');
     s = fs.readlinkSync('/path/to/folder', undefined);
@@ -203,8 +202,6 @@ async function testPromisify() {
     s = fs.readlinkSync('/path/to/folder', { encoding: undefined });
     s = fs.readlinkSync('/path/to/folder', { encoding: 'utf8' });
     b = fs.readlinkSync('/path/to/folder', { encoding: 'buffer' });
-    const v2 = fs.readlinkSync('/path/to/folder', { encoding: s });
-    typeof v2 === "string" ? s = v2 : b = v2;
 }
 
 {
@@ -219,7 +216,6 @@ async function testPromisify() {
     fs.realpath('/path/to/folder', { encoding: undefined }, (err, resolvedPath) => s = resolvedPath);
     fs.realpath('/path/to/folder', { encoding: 'utf8' }, (err, resolvedPath) => s = resolvedPath);
     fs.realpath('/path/to/folder', { encoding: 'buffer' }, (err, resolvedPath) => b = resolvedPath);
-    fs.realpath('/path/to/folder', { encoding: s }, (err, resolvedPath) => typeof resolvedPath === "string" ? s = resolvedPath : b = resolvedPath);
 
     s = fs.realpathSync('/path/to/folder');
     s = fs.realpathSync('/path/to/folder', undefined);
@@ -232,8 +228,6 @@ async function testPromisify() {
     s = fs.realpathSync('/path/to/folder', { encoding: undefined });
     s = fs.realpathSync('/path/to/folder', { encoding: 'utf8' });
     b = fs.realpathSync('/path/to/folder', { encoding: 'buffer' });
-    const v2 = fs.realpathSync('/path/to/folder', { encoding: s });
-    typeof v2 === "string" ? s = v2 : b = v2;
 
     // native
     fs.realpath.native('/path/to/folder', (err, resolvedPath) => s = resolvedPath);
@@ -245,7 +239,6 @@ async function testPromisify() {
     fs.realpath.native('/path/to/folder', { encoding: undefined }, (err, resolvedPath) => s = resolvedPath);
     fs.realpath.native('/path/to/folder', { encoding: 'utf8' }, (err, resolvedPath) => s = resolvedPath);
     fs.realpath.native('/path/to/folder', { encoding: 'buffer' }, (err, resolvedPath) => b = resolvedPath);
-    fs.realpath.native('/path/to/folder', { encoding: s }, (err, resolvedPath) => typeof resolvedPath === "string" ? s = resolvedPath : b = resolvedPath);
 
     s = fs.realpathSync.native('/path/to/folder');
     s = fs.realpathSync.native('/path/to/folder', undefined);
@@ -258,8 +251,6 @@ async function testPromisify() {
     s = fs.realpathSync.native('/path/to/folder', { encoding: undefined });
     s = fs.realpathSync.native('/path/to/folder', { encoding: 'utf8' });
     b = fs.realpathSync.native('/path/to/folder', { encoding: 'buffer' });
-    const v4 = fs.realpathSync.native('/path/to/folder', { encoding: s });
-    typeof v4 === "string" ? s = v4 : b = v4;
 }
 
 {
@@ -307,12 +298,10 @@ async function testPromisify() {
 {
     let names: Promise<string[]>;
     let buffers: Promise<Buffer[]>;
-    let namesOrBuffers: Promise<string[] | Buffer[]>;
     let entries: Promise<fs.Dirent[]>;
 
     names = fs.promises.readdir('/path/to/dir', { encoding: 'utf8', withFileTypes: false });
     buffers = fs.promises.readdir('/path/to/dir', { encoding: 'buffer', withFileTypes: false });
-    namesOrBuffers = fs.promises.readdir('/path/to/dir', { encoding: 'SOME OTHER', withFileTypes: false });
     entries = fs.promises.readdir('/path/to/dir', { encoding: 'utf8', withFileTypes: true });
 }
 
diff --git a/types/node/test/stream.ts b/types/node/test/stream.ts
index 9272e19c2f..9416a94ae0 100644
--- a/types/node/test/stream.ts
+++ b/types/node/test/stream.ts
@@ -27,7 +27,7 @@ function simplified_stream_ctor_test() {
             this;
             // $ExpectType any
             chunk;
-            // $ExpectType string
+            // $ExpectType BufferEncoding
             enc;
             // $ExpectType (error?: Error | null | undefined) => void
             cb;
@@ -35,7 +35,7 @@ function simplified_stream_ctor_test() {
         writev(chunks, cb) {
             // $ExpectType Writable
             this;
-            // $ExpectType { chunk: any; encoding: string; }[]
+            // $ExpectType { chunk: any; encoding: BufferEncoding; }[]
             chunks;
             // $ExpectType (error?: Error | null | undefined) => void
             cb;
@@ -68,7 +68,7 @@ function simplified_stream_ctor_test() {
             this;
             // $ExpectType any
             chunk;
-            // $ExpectType string
+            // $ExpectType BufferEncoding
             enc;
             // $ExpectType (error?: Error | null | undefined) => void
             cb;
@@ -76,7 +76,7 @@ function simplified_stream_ctor_test() {
         writev(chunks, cb) {
             // $ExpectType Duplex
             this;
-            // $ExpectType { chunk: any; encoding: string; }[]
+            // $ExpectType { chunk: any; encoding: BufferEncoding; }[]
             chunks;
             // $ExpectType (error?: Error | null | undefined) => void
             cb;
@@ -113,7 +113,7 @@ function simplified_stream_ctor_test() {
             this;
             // $ExpectType any
             chunk;
-            // $ExpectType string
+            // $ExpectType BufferEncoding
             enc;
             // $ExpectType (error?: Error | null | undefined) => void
             cb;
@@ -121,7 +121,7 @@ function simplified_stream_ctor_test() {
         writev(chunks, cb) {
             // $ExpectType Transform
             this;
-            // $ExpectType { chunk: any; encoding: string; }[]
+            // $ExpectType { chunk: any; encoding: BufferEncoding; }[]
             chunks;
             // $ExpectType (error?: Error | null | undefined) => void
             cb;
@@ -145,7 +145,7 @@ function simplified_stream_ctor_test() {
             this;
             // $ExpectType any
             chunk;
-            // $ExpectType string
+            // $ExpectType BufferEncoding
             enc;
             // $ExpectType TransformCallback
             cb;
diff --git a/types/node/v13/assert.d.ts b/types/node/v13/assert.d.ts
index df6df63fc0..6a6f43dc55 100644
--- a/types/node/v13/assert.d.ts
+++ b/types/node/v13/assert.d.ts
@@ -1,6 +1,6 @@
 declare module "assert" {
-    function internal(value: any, message?: string | Error): void;
-    namespace internal {
+    function assert(value: any, message?: string | Error): void;
+    namespace assert {
         class AssertionError implements Error {
             name: string;
             message: string;
@@ -22,9 +22,13 @@ declare module "assert" {
         /** @deprecated since v10.0.0 - use fail([message]) or other assert functions instead. */
         function fail(actual: any, expected: any, message?: string | Error, operator?: string, stackStartFn?: Function): never;
         function ok(value: any, message?: string | Error): void;
+        /** @deprecated since v9.9.0 - use strictEqual() instead. */
         function equal(actual: any, expected: any, message?: string | Error): void;
+        /** @deprecated since v9.9.0 - use notStrictEqual() instead. */
         function notEqual(actual: any, expected: any, message?: string | Error): void;
+        /** @deprecated since v9.9.0 - use deepStrictEqual() instead. */
         function deepEqual(actual: any, expected: any, message?: string | Error): void;
+        /** @deprecated since v9.9.0 - use notDeepStrictEqual() instead. */
         function notDeepEqual(actual: any, expected: any, message?: string | Error): void;
         function strictEqual(actual: any, expected: any, message?: string | Error): void;
         function notStrictEqual(actual: any, expected: any, message?: string | Error): void;
@@ -46,8 +50,8 @@ declare module "assert" {
         function match(value: string, regExp: RegExp, message?: string | Error): void;
         function doesNotMatch(value: string, regExp: RegExp, message?: string | Error): void;
 
-        const strict: typeof internal;
+        const strict: typeof assert;
     }
 
-    export = internal;
+    export = assert;
 }
diff --git a/types/node/v13/base.d.ts b/types/node/v13/base.d.ts
index 70983d9515..ad04bb3065 100644
--- a/types/node/v13/base.d.ts
+++ b/types/node/v13/base.d.ts
@@ -1,6 +1,5 @@
 // base definnitions for all NodeJS modules that are not specific to any version of TypeScript
 /// <reference path="globals.d.ts" />
-/// <reference path="assert.d.ts" />
 /// <reference path="async_hooks.d.ts" />
 /// <reference path="buffer.d.ts" />
 /// <reference path="child_process.d.ts" />
diff --git a/types/node/v13/index.d.ts b/types/node/v13/index.d.ts
index 0073973e6c..0d6de51604 100644
--- a/types/node/v13/index.d.ts
+++ b/types/node/v13/index.d.ts
@@ -59,6 +59,9 @@
 // Base definitions for all NodeJS modules that are not specific to any version of TypeScript:
 /// <reference path="base.d.ts" />
 
+// We can't include assert.d.ts in base.d.ts, as it'll cause duplication errors in +ts3.7
+/// <reference path="assert.d.ts" />
+
 // Forward-declarations for needed types from es2015 and later (in case users are using `--lib es5`)
 // Empty interfaces are used here which merge fine with the real declarations in the lib XXX files
 // just to ensure the names are known and node typings can be used without importing these libs.
diff --git a/types/node/v13/package.json b/types/node/v13/package.json
index 933bc00739..f791e46a8a 100644
--- a/types/node/v13/package.json
+++ b/types/node/v13/package.json
@@ -2,6 +2,11 @@
     "private": true,
     "types": "index",
     "typesVersions": {
+        ">=3.7.0-0": {
+            "*": [
+                "ts3.7/*"
+            ]
+        },
         ">=3.5.0-0": {
             "*": [
                 "ts3.5/*"
diff --git a/types/node/v13/ts3.2/base.d.ts b/types/node/v13/ts3.2/base.d.ts
new file mode 100644
index 0000000000..bb6f5ca621
--- /dev/null
+++ b/types/node/v13/ts3.2/base.d.ts
@@ -0,0 +1,22 @@
+// NOTE: These definitions support NodeJS and TypeScript 3.2.
+
+// NOTE: TypeScript version-specific augmentations can be found in the following paths:
+//          - ~/base.d.ts         - Shared definitions common to all TypeScript versions
+//          - ~/index.d.ts        - Definitions specific to TypeScript 2.1
+//          - ~/ts3.2/base.d.ts   - Definitions specific to TypeScript 3.2
+//          - ~/ts3.2/index.d.ts  - Definitions specific to TypeScript 3.2 with assert pulled in
+
+// Reference required types from the default lib:
+/// <reference lib="es2018" />
+/// <reference lib="esnext.asynciterable" />
+/// <reference lib="esnext.intl" />
+/// <reference lib="esnext.bigint" />
+
+// Base definitions for all NodeJS modules that are not specific to any version of TypeScript:
+// tslint:disable-next-line:no-bad-reference
+/// <reference path="../base.d.ts" />
+
+// TypeScript 3.2-specific augmentations:
+/// <reference path="fs.d.ts" />
+/// <reference path="util.d.ts" />
+/// <reference path="globals.d.ts" />
diff --git a/types/node/v13/ts3.2/index.d.ts b/types/node/v13/ts3.2/index.d.ts
index 4814cd8dfd..3f1c54b1d9 100644
--- a/types/node/v13/ts3.2/index.d.ts
+++ b/types/node/v13/ts3.2/index.d.ts
@@ -1,16 +1,8 @@
 // NOTE: These definitions support NodeJS and TypeScript 3.2.
+// This is requried to enable typing assert in ts3.7 without causing errors
+// Typically type modifiations should be made in base.d.ts instead of here
 
-// Reference required types from the default lib:
-/// <reference lib="es2018" />
-/// <reference lib="esnext.asynciterable" />
-/// <reference lib="esnext.intl" />
-/// <reference lib="esnext.bigint" />
+/// <reference path="base.d.ts" />
 
-// Base definitions for all NodeJS modules that are not specific to any version of TypeScript:
 // tslint:disable-next-line:no-bad-reference
-/// <reference path="../base.d.ts" />
-
-// TypeScript 3.2-specific augmentations:
-/// <reference path="fs.d.ts" />
-/// <reference path="util.d.ts" />
-/// <reference path="globals.d.ts" />
+/// <reference path="../assert.d.ts" />
diff --git a/types/node/v13/ts3.5/base.d.ts b/types/node/v13/ts3.5/base.d.ts
new file mode 100644
index 0000000000..5cbe3943ad
--- /dev/null
+++ b/types/node/v13/ts3.5/base.d.ts
@@ -0,0 +1,20 @@
+// NOTE: These definitions support NodeJS and TypeScript 3.5.
+
+// NOTE: TypeScript version-specific augmentations can be found in the following paths:
+//          - ~/base.d.ts         - Shared definitions common to all TypeScript versions
+//          - ~/index.d.ts        - Definitions specific to TypeScript 2.1
+//          - ~/ts3.5/base.d.ts   - Definitions specific to TypeScript 3.5
+//          - ~/ts3.5/index.d.ts  - Definitions specific to TypeScript 3.5 with assert pulled in
+
+// Reference required types from the default lib:
+/// <reference lib="es2018" />
+/// <reference lib="esnext.asynciterable" />
+/// <reference lib="esnext.intl" />
+/// <reference lib="esnext.bigint" />
+
+// Base definitions for all NodeJS modules that are not specific to any version of TypeScript:
+// tslint:disable-next-line:no-bad-reference
+/// <reference path="../ts3.2/base.d.ts" />
+
+// TypeScript 3.5-specific augmentations:
+/// <reference path="wasi.d.ts" />
diff --git a/types/node/v13/ts3.5/index.d.ts b/types/node/v13/ts3.5/index.d.ts
index a57c5eff7c..4b983c6d5a 100644
--- a/types/node/v13/ts3.5/index.d.ts
+++ b/types/node/v13/ts3.5/index.d.ts
@@ -1,14 +1,8 @@
 // NOTE: These definitions support NodeJS and TypeScript 3.5.
+// This is requried to enable typing assert in ts3.7 without causing errors
+// Typically type modifiations should be made in base.d.ts instead of here
 
-// Reference required types from the default lib:
-/// <reference lib="es2018" />
-/// <reference lib="esnext.asynciterable" />
-/// <reference lib="esnext.intl" />
-/// <reference lib="esnext.bigint" />
+/// <reference path="base.d.ts" />
 
-// Base definitions for all NodeJS modules that are not specific to any version of TypeScript:
 // tslint:disable-next-line:no-bad-reference
-/// <reference path="../ts3.2/index.d.ts" />
-
-// TypeScript 3.5-specific augmentations:
-/// <reference path="wasi.d.ts" />
+/// <reference path="../assert.d.ts" />
diff --git a/types/node/v13/ts3.7/assert.d.ts b/types/node/v13/ts3.7/assert.d.ts
new file mode 100644
index 0000000000..9750dae7de
--- /dev/null
+++ b/types/node/v13/ts3.7/assert.d.ts
@@ -0,0 +1,57 @@
+declare module "assert" {
+    function assert(value: any, message?: string | Error): asserts value;
+    namespace assert {
+        class AssertionError implements Error {
+            name: string;
+            message: string;
+            actual: any;
+            expected: any;
+            operator: string;
+            generatedMessage: boolean;
+            code: 'ERR_ASSERTION';
+
+            constructor(options?: {
+                message?: string; actual?: any; expected?: any;
+                operator?: string; stackStartFn?: Function
+            });
+        }
+
+        type AssertPredicate = RegExp | (new() => object) | ((thrown: any) => boolean) | object | Error;
+
+        function fail(message?: string | Error): never;
+        /** @deprecated since v10.0.0 - use fail([message]) or other assert functions instead. */
+        function fail(actual: any, expected: any, message?: string | Error, operator?: string, stackStartFn?: Function): never;
+        function ok(value: any, message?: string | Error): asserts value;
+        /** @deprecated since v9.9.0 - use strictEqual() instead. */
+        function equal(actual: any, expected: any, message?: string | Error): void;
+        /** @deprecated since v9.9.0 - use notStrictEqual() instead. */
+        function notEqual(actual: any, expected: any, message?: string | Error): void;
+        /** @deprecated since v9.9.0 - use deepStrictEqual() instead. */
+        function deepEqual(actual: any, expected: any, message?: string | Error): void;
+        /** @deprecated since v9.9.0 - use notDeepStrictEqual() instead. */
+        function notDeepEqual(actual: any, expected: any, message?: string | Error): void;
+        function strictEqual<T>(actual: any, expected: T, message?: string | Error): asserts actual is T;
+        function notStrictEqual(actual: any, expected: any, message?: string | Error): void;
+        function deepStrictEqual<T>(actual: any, expected: T, message?: string | Error): asserts actual is T;
+        function notDeepStrictEqual(actual: any, expected: any, message?: string | Error): void;
+
+        function throws(block: () => any, message?: string | Error): void;
+        function throws(block: () => any, error: AssertPredicate, message?: string | Error): void;
+        function doesNotThrow(block: () => any, message?: string | Error): void;
+        function doesNotThrow(block: () => any, error: RegExp | Function, message?: string | Error): void;
+
+        function ifError(value: any): asserts value is null | undefined;
+
+        function rejects(block: (() => Promise<any>) | Promise<any>, message?: string | Error): Promise<void>;
+        function rejects(block: (() => Promise<any>) | Promise<any>, error: AssertPredicate, message?: string | Error): Promise<void>;
+        function doesNotReject(block: (() => Promise<any>) | Promise<any>, message?: string | Error): Promise<void>;
+        function doesNotReject(block: (() => Promise<any>) | Promise<any>, error: RegExp | Function, message?: string | Error): Promise<void>;
+
+        function match(value: string, regExp: RegExp, message?: string | Error): void;
+        function doesNotMatch(value: string, regExp: RegExp, message?: string | Error): void;
+
+        const strict: typeof assert;
+    }
+
+    export = assert;
+}
diff --git a/types/node/v13/ts3.7/base.d.ts b/types/node/v13/ts3.7/base.d.ts
new file mode 100644
index 0000000000..201cd5678b
--- /dev/null
+++ b/types/node/v13/ts3.7/base.d.ts
@@ -0,0 +1,20 @@
+// NOTE: These definitions support NodeJS and TypeScript 3.7.
+
+// NOTE: TypeScript version-specific augmentations can be found in the following paths:
+//          - ~/base.d.ts         - Shared definitions common to all TypeScript versions
+//          - ~/index.d.ts        - Definitions specific to TypeScript 2.1
+//          - ~/ts3.7/base.d.ts   - Definitions specific to TypeScript 3.7
+//          - ~/ts3.7/index.d.ts  - Definitions specific to TypeScript 3.7 with assert pulled in
+
+// Reference required types from the default lib:
+/// <reference lib="es2018" />
+/// <reference lib="esnext.asynciterable" />
+/// <reference lib="esnext.intl" />
+/// <reference lib="esnext.bigint" />
+
+// Base definitions for all NodeJS modules that are not specific to any version of TypeScript:
+// tslint:disable-next-line:no-bad-reference
+/// <reference path="../ts3.5/base.d.ts" />
+
+// TypeScript 3.7-specific augmentations:
+/// <reference path="assert.d.ts" />
diff --git a/types/node/v13/ts3.7/index.d.ts b/types/node/v13/ts3.7/index.d.ts
new file mode 100644
index 0000000000..2cd553b853
--- /dev/null
+++ b/types/node/v13/ts3.7/index.d.ts
@@ -0,0 +1,5 @@
+// NOTE: These definitions support NodeJS and TypeScript 3.7.
+// This isn't strictly needed since 3.7 has the assert module, but this way we're consistent.
+// Typically type modificatons should be made in base.d.ts instead of here
+
+/// <reference path="base.d.ts" />
diff --git a/types/node/v13/ts3.7/node-tests.ts b/types/node/v13/ts3.7/node-tests.ts
new file mode 100644
index 0000000000..983748c1fd
--- /dev/null
+++ b/types/node/v13/ts3.7/node-tests.ts
@@ -0,0 +1,59 @@
+import * as assert from 'assert';
+
+assert(true, "it's working");
+
+assert.ok(true, 'inner functions work as well');
+
+assert.throws(() => {});
+assert.throws(() => {}, /Regex test/);
+assert.throws(
+    () => {},
+    () => {},
+    'works wonderfully',
+);
+
+assert['fail'](true, true, 'works like a charm');
+
+{
+    const a = null as any;
+    assert.ifError(a);
+    a; // $ExpectType null | undefined
+}
+
+{
+    const a = true as boolean;
+    assert(a);
+    a; // $ExpectType true
+}
+
+{
+    // tslint:disable-next-line: no-null-undefined-union
+    const a = 13 as number | null | undefined;
+    assert(a);
+    a; // $ExpectType number
+}
+
+{
+    const a = true as boolean;
+    assert.ok(a);
+    a; // $ExpectType true
+}
+
+{
+    // tslint:disable-next-line: no-null-undefined-union
+    const a = 13 as number | null | undefined;
+    assert.ok(a);
+    a; // $ExpectType number
+}
+
+{
+    const a = 'test' as any;
+    assert.strictEqual(a, 'test');
+    a; // $ExpectType string
+}
+
+{
+    const a = { b: 2 } as any;
+    assert.deepStrictEqual(a, { b: 2 });
+    a; // $ExpectType { b: number; }
+}
diff --git a/types/node/v13/ts3.7/tsconfig.json b/types/node/v13/ts3.7/tsconfig.json
new file mode 100644
index 0000000000..e2e30153f8
--- /dev/null
+++ b/types/node/v13/ts3.7/tsconfig.json
@@ -0,0 +1,30 @@
+{
+    "files": [
+        "index.d.ts",
+        "node-tests.ts"
+    ],
+    "compilerOptions": {
+        "module": "commonjs",
+        "target": "esnext",
+        "lib": [
+            "es6",
+            "dom"
+        ],
+        "noImplicitAny": true,
+        "noImplicitThis": true,
+        "strictNullChecks": true,
+        "strictFunctionTypes": true,
+        "baseUrl": "../../../",
+        "typeRoots": [
+            "../../../"
+        ],
+        "paths": {
+            "node": [
+                "node/v13"
+            ]
+        },
+        "types": [],
+        "noEmit": true,
+        "forceConsistentCasingInFileNames": true
+    }
+}
diff --git a/types/node/v13/ts3.7/tslint.json b/types/node/v13/ts3.7/tslint.json
new file mode 100644
index 0000000000..1a8ddd9863
--- /dev/null
+++ b/types/node/v13/ts3.7/tslint.json
@@ -0,0 +1,10 @@
+{
+  "extends": "dtslint/dt.json",
+  "rules": {
+    "ban-types": false,
+    "unified-signatures": false,
+    "no-empty-interface": false,
+    "no-single-declare-module": false,
+    "strict-export-declare-modifiers": false // http2 needs this
+  }
+}
diff --git a/types/object-hash/index.d.ts b/types/object-hash/index.d.ts
index ce45749d08..8cd7273711 100644
--- a/types/object-hash/index.d.ts
+++ b/types/object-hash/index.d.ts
@@ -4,8 +4,8 @@
 // Definitions: https://github.com/DefinitelyTyped/DefinitelyTyped
 
 interface IStream {
-    update?(chunk: any, encoding: string, callback: (error?: Error | null) => void): void;
-    write?(chunk: any, encoding: string, callback: (error?: Error | null) => void): void;
+    update?(chunk: any, encoding: BufferEncoding, callback: (error?: Error | null) => void): void;
+    write?(chunk: any, encoding: BufferEncoding, callback: (error?: Error | null) => void): void;
 }
 
 import HashStatic = ObjectHash.HashStatic;
diff --git a/types/read-json-sync/read-json-sync-tests.ts b/types/read-json-sync/read-json-sync-tests.ts
index 2c4c14e5ec..10e2ea49f4 100644
--- a/types/read-json-sync/read-json-sync-tests.ts
+++ b/types/read-json-sync/read-json-sync-tests.ts
@@ -1,4 +1,4 @@
 import readJsonSync = require("read-json-sync");
 
 readJsonSync("file.json", "utf8");
-readJsonSync(1, { encoding: "gb2312" });
+readJsonSync(1, { encoding: "utf8" });
diff --git a/types/readable-stream/index.d.ts b/types/readable-stream/index.d.ts
index 4c2ad6f663..f68f0a2014 100644
--- a/types/readable-stream/index.d.ts
+++ b/types/readable-stream/index.d.ts
@@ -6,7 +6,6 @@
 
 /// <reference types="node" />
 
-import * as events from "events";
 import * as stream from "stream";
 import * as SafeBuffer from "safe-buffer";
 import { StringDecoder } from "string_decoder";
@@ -54,8 +53,8 @@ declare namespace _Readable {
         readable?: boolean;
         writable?: boolean;
         read?(this: Duplex, size: number): void;
-        write?(this: Duplex, chunk: any, encoding: string, callback: (error?: Error | null) => void): void;
-        writev?(this: Duplex, chunks: Array<{ chunk: any, encoding: string }>, callback: (error?: Error | null) => void): void;
+        write?(this: Duplex, chunk: any, encoding: BufferEncoding, callback: (error?: Error | null) => void): void;
+        writev?(this: Duplex, chunks: Array<{ chunk: any, encoding: BufferEncoding }>, callback: (error?: Error | null) => void): void;
         final?(this: Duplex, callback: (error?: Error | null) => void): void;
         destroy?(this: Duplex, error: Error | null, callback: (error: Error | null) => void): void;
     };
@@ -77,14 +76,14 @@ declare namespace _Readable {
 
         _read(size?: number): void;
         read(size?: number): any;
-        setEncoding(enc: string): this;
+        setEncoding(enc: BufferEncoding): this;
         resume(): this;
         pause(): this;
         isPaused(): boolean;
         unpipe(dest?: NodeJS.WritableStream): this;
         unshift(chunk: any): boolean;
         wrap(oldStream: NodeJS.ReadableStream): this;
-        push(chunk: any, encoding?: string): boolean;
+        push(chunk: any, encoding?: BufferEncoding): boolean;
         _destroy(err: Error | null, callback: (error: Error | null) => void): void;
         destroy(err?: Error, callback?: (error: Error | null) => void): this;
         pipe<S extends NodeJS.WritableStream>(dest: S, pipeOpts?: { end?: boolean }): S;
@@ -102,13 +101,13 @@ declare namespace _Readable {
     class PassThrough extends Transform implements stream.PassThrough {
         constructor(options?: TransformOptions);
 
-        _transform<T>(chunk: T, encoding: string | null | undefined, callback: (error: any, data: T) => void): void;
+        _transform<T>(chunk: T, encoding: BufferEncoding | null | undefined, callback: (error: any, data: T) => void): void;
     }
 
     // ==== _stream_readable ====
     interface ReadableStateOptions {
-        defaultEncoding?: string;
-        encoding?: string;
+        defaultEncoding?: BufferEncoding;
+        encoding?: BufferEncoding;
         highWaterMark?: number;
         objectMode?: boolean;
         readableObjectMode?: boolean;
@@ -133,10 +132,10 @@ declare namespace _Readable {
         resumeScheduled: boolean;
         destroyed: boolean;
         awaitDrain: number;
-        defaultEncoding: string;
+        defaultEncoding: BufferEncoding;
         readingMore: boolean;
         decoder: StringDecoder | null;
-        encoding: string | null;
+        encoding: BufferEncoding | null;
 
         // new (options: ReadableStateOptions, stream: _Readable): ReadableState;
     }
@@ -153,11 +152,11 @@ declare namespace _Readable {
     // ==== _stream_transform ====
     type TransformOptions = DuplexOptions & {
         read?(this: Transform, size: number): void;
-        write?(this: Transform, chunk: any, encoding: string, callback: (error?: Error | null) => void): void;
-        writev?(this: Transform, chunks: Array<{ chunk: any, encoding: string }>, callback: (error?: Error | null) => void): void;
+        write?(this: Transform, chunk: any, encoding: BufferEncoding, callback: (error?: Error | null) => void): void;
+        writev?(this: Transform, chunks: Array<{ chunk: any, encoding: BufferEncoding }>, callback: (error?: Error | null) => void): void;
         final?(this: Transform, callback: (error?: Error | null) => void): void;
         destroy?(this: Transform, error: Error | null, callback: (error: Error | null) => void): void;
-        transform?(this: Transform, chunk: any, encoding: string, callback: (error?: Error, data?: any) => void): void;
+        transform?(this: Transform, chunk: any, encoding: BufferEncoding, callback: (error?: Error, data?: any) => void): void;
         flush?(this: Transform, callback: (er: any, data: any) => void): void;
     };
 
@@ -168,12 +167,12 @@ declare namespace _Readable {
             transforming: boolean;
             writecb: ((err: any) => any) | null;
             writechunk: any; // TODO
-            writeencoding: string | null;
+            writeencoding: BufferEncoding | null;
         };
 
         constructor(options?: TransformOptions);
 
-        _transform(chunk: any, encoding: string, callback: (error?: Error, data?: any) => void): void;
+        _transform(chunk: any, encoding: BufferEncoding, callback: (error?: Error, data?: any) => void): void;
         _flush(callback: (error?: Error, data?: any) => void): void;
     }
 
@@ -186,7 +185,7 @@ declare namespace _Readable {
 
     interface BufferRequest {
         chunk: any; // TODO
-        encoding: string;
+        encoding: BufferEncoding;
         isBuf: boolean;
         callback: (error?: Error | null) => void;
         next: BufferRequest | null;
@@ -194,7 +193,7 @@ declare namespace _Readable {
 
     interface WritableStateOptions {
         decodeStrings?: boolean;
-        defaultEncoding?: string;
+        defaultEncoding?: BufferEncoding;
         highWaterMark?: number;
         objectMode?: boolean;
         writableObjectMode?: boolean;
@@ -212,7 +211,7 @@ declare namespace _Readable {
         finished: boolean;
         destroyed: boolean;
         decodeStrings: boolean;
-        defaultEncoding: string;
+        defaultEncoding: BufferEncoding;
         length: number;
         writing: boolean;
         corked: number;
@@ -235,8 +234,8 @@ declare namespace _Readable {
     }
 
     type WritableOptions = WritableStateOptions & {
-        write?(this: Writable, chunk: any, encoding: string, callback: (error?: Error | null) => void): void;
-        writev?(this: Writable, chunk: ArrayLike<{ chunk: any; encoding: string }>, callback: (error?: Error | null) => void): void;
+        write?(this: Writable, chunk: any, encoding: BufferEncoding, callback: (error?: Error | null) => void): void;
+        writev?(this: Writable, chunk: ArrayLike<{ chunk: any; encoding: BufferEncoding }>, callback: (error?: Error | null) => void): void;
         destroy?(this: Writable, error: Error | null, callback: (error: Error | null) => void): void;
         final?(this: Writable, callback: (error?: Error | null) => void): void;
     };
diff --git a/types/resolve/index.d.ts b/types/resolve/index.d.ts
index 48c550f536..3f5c748030 100644
--- a/types/resolve/index.d.ts
+++ b/types/resolve/index.d.ts
@@ -115,7 +115,7 @@ declare namespace resolve {
 
   export interface SyncOpts extends Opts {
     /** how to read files synchronously (defaults to fs.readFileSync) */
-    readFileSync?: (file: string, charset: string) => string | Buffer;
+    readFileSync?: (file: string, encoding: BufferEncoding) => string | Buffer;
     /** function to synchronously test whether a file exists */
     isFile?: (file: string) => boolean;
     /** function to synchronously test whether a directory exists */
diff --git a/types/snappy/snappy-tests.ts b/types/snappy/snappy-tests.ts
index d44d9aee13..b55298bc3a 100644
--- a/types/snappy/snappy-tests.ts
+++ b/types/snappy/snappy-tests.ts
@@ -13,7 +13,7 @@ snappy.uncompress(data, (err, data) => {
   if (err) {
     throw err;
   }
-  console.log(data.toString('UTF8'));
+  console.log(data.toString('utf8'));
 });
 snappy.uncompress(otherData, { asBuffer: false }, (err, original) => {
   if (err) {
diff --git a/types/snekfetch/snekfetch-tests.ts b/types/snekfetch/snekfetch-tests.ts
index 211ef5bd80..c4070d0067 100644
--- a/types/snekfetch/snekfetch-tests.ts
+++ b/types/snekfetch/snekfetch-tests.ts
@@ -5,7 +5,7 @@ import snekfetch = require('snekfetch');
 const writeFile = util.promisify(fs.writeFile);
 
 snekfetch.get('https://s.gus.host/o-SNAKES-80.jpg')
-  .then(r => writeFile('download.jpg', r.body));
+  .then(r => writeFile('download.jpg', r.body as (string | Buffer)));
 
 snekfetch.get('https://s.gus.host/o-SNAKES-80.jpg')
   .pipe(fs.createWriteStream('download.jpg'));
diff --git a/types/through2/index.d.ts b/types/through2/index.d.ts
index e24c15a3e3..412e5e46ca 100644
--- a/types/through2/index.d.ts
+++ b/types/through2/index.d.ts
@@ -22,7 +22,7 @@ declare namespace through2 {
     }
 
     type TransformCallback = (err?: any, data?: any) => void;
-    type TransformFunction = (this: stream.Transform, chunk: any, enc: string, callback: TransformCallback) => void;
+    type TransformFunction = (this: stream.Transform, chunk: any, enc: BufferEncoding, callback: TransformCallback) => void;
     type FlushCallback = (this: stream.Transform, flushCallback: () => void) => void;
 
 	/**
diff --git a/types/through2/through2-tests.ts b/types/through2/through2-tests.ts
index e1de34f3a9..48af040844 100644
--- a/types/through2/through2-tests.ts
+++ b/types/through2/through2-tests.ts
@@ -24,8 +24,7 @@ rws = through2(function (entry: any, enc: string, callback: () => void) {
 });
 
 rws = through2(function (entry, enc, callback) {
-    var str: string = enc;
-    this.push(entry, str);
+    this.push(entry, enc);
     callback(null, 'continue');
 }, () => {