diff --git a/types/nodegit/commit.d.ts b/types/nodegit/commit.d.ts
index 57e8c55d87..8152eb8a8d 100644
--- a/types/nodegit/commit.d.ts
+++ b/types/nodegit/commit.d.ts
@@ -25,7 +25,7 @@ export class Commit {
     static lookupPrefix(repo: Repository, id: Oid, len: number): Promise<Commit>;
     static createWithSignature(repo: Repository, commitContent: string, signature: string, signatureField: string): Promise<Oid>;
 
-    amend(updateRef: string, author: Signature, committer: Signature, messageEncoding: string, message: string, tree: Tree): Promise<Oid>;
+    amend(updateRef: string, author: Signature, committer: Signature, messageEncoding: string, message: string, tree: Tree | Oid): Promise<Oid>;
     author(): Signature;
     committer(): Signature;
 
diff --git a/types/nodegit/diff.d.ts b/types/nodegit/diff.d.ts
index 62de0de6c4..2f1abbda62 100644
--- a/types/nodegit/diff.d.ts
+++ b/types/nodegit/diff.d.ts
@@ -132,17 +132,18 @@ export class Diff {
      *
      *
      */
-    static blobToBuffer(oldBlob: Blob, oldAsPath: string,
-                        buffer: string, bufferAsPath: string, opts: DiffOptions, fileCb: Function, binaryCb: Function, hunkCb: Function, lineCb: Function): Promise<any>;
+    static blobToBuffer(oldBlob: Blob | null, oldAsPath: string | null,
+                        buffer: string | null, bufferAsPath: string | null, opts: DiffOptions | null, fileCb: Function | null,
+                        binaryCb: Function | null, hunkCb: Function | null, lineCb: Function): Promise<any>;
     static fromBuffer(content: string, contentLen: number): Promise<Diff>;
-    static indexToWorkdir(repo: Repository, index: Index, opts?: DiffOptions): Promise<Diff>;
+    static indexToWorkdir(repo: Repository, index: Index | null, opts?: DiffOptions): Promise<Diff>;
     static indexToIndex(repo: Repository, oldIndex: Index, newIndex: Index, opts?: DiffOptions): Promise<Diff>;
-    static treeToIndex(repo: Repository, oldTree: Tree, index: Index, opts?: DiffOptions): Promise<Diff>;
-    static treeToTree(repo: Repository, oldTree: Tree, new_tree: Tree, opts?: DiffOptions): Promise<Diff>;
-    static treeToWorkdir(repo: Repository, oldTree: Tree, opts?: DiffOptions): Promise<Diff>;
-    static treeToWorkdirWithIndex(repo: Repository, oldTree: Tree, opts?: DiffOptions): Promise<Diff>;
+    static treeToIndex(repo: Repository, oldTree: Tree | null, index: Index | null, opts?: DiffOptions): Promise<Diff>;
+    static treeToTree(repo: Repository, oldTree: Tree | null, new_tree: Tree | null, opts?: DiffOptions): Promise<Diff>;
+    static treeToWorkdir(repo: Repository, oldTree: Tree | null, opts?: DiffOptions): Promise<Diff>;
+    static treeToWorkdirWithIndex(repo: Repository, oldTree: Tree | null, opts?: DiffOptions): Promise<Diff>;
 
-    findSimilar(options: DiffFindOptions): Promise<number>;
+    findSimilar(options?: DiffFindOptions): Promise<number>;
     getDelta(idx: number): DiffDelta;
     getPerfdata(): Promise<DiffPerfdata>;
     numDeltas(): number;
diff --git a/types/nodegit/index.d.ts b/types/nodegit/index.d.ts
index 8f0dd811a0..c0e18853a6 100644
--- a/types/nodegit/index.d.ts
+++ b/types/nodegit/index.d.ts
@@ -1,6 +1,8 @@
 // Type definitions for nodegit 0.24
 // Project: https://github.com/nodegit/nodegit, http://nodegit.org
-// Definitions by: Dolan Miu <https://github.com/dolanmiu>, Tobias Nießen <https://github.com/tniessen>
+// Definitions by: Dolan Miu <https://github.com/dolanmiu>,
+//                 Tobias Nießen <https://github.com/tniessen>,
+//                 Pierre Vigier <https://github.com/pvigier>
 // Definitions: https://github.com/DefinitelyTyped/DefinitelyTyped
 
 export { AnnotatedCommit } from './annotated-commit';
diff --git a/types/nodegit/reset.d.ts b/types/nodegit/reset.d.ts
index 9051fa693b..ca7ff41e86 100644
--- a/types/nodegit/reset.d.ts
+++ b/types/nodegit/reset.d.ts
@@ -1,8 +1,9 @@
 import { AnnotatedCommit } from './annotated-commit';
 import { Repository } from './repository';
-import { Object } from './object';
 import { Strarray } from './str-array';
 import { CheckoutOptions } from './checkout-options';
+import { Commit } from './commit';
+import { Tag } from './tag';
 
 export namespace Reset {
     const enum TYPE {
@@ -16,11 +17,11 @@ export class Reset {
     /**
      * Look up a refs's commit.
      */
-    static reset(repo: Repository, target: Object, resetType: number, checkoutOpts: CheckoutOptions): Promise<number>;
+    static reset(repo: Repository, target: Commit | Tag, resetType: number, checkoutOpts: CheckoutOptions): Promise<number>;
     /**
      * Look up a refs's commit.
      */
-    static default(repo: Repository, target: Object, pathspecs: Strarray | string | string[]): Promise<number>;
+    static default(repo: Repository, target: Commit | Tag, pathspecs: Strarray | string | string[]): Promise<number>;
     /**
      * Sets the current head to the specified commit oid and optionally resets the index and working tree to match.
      * This behaves like reset but takes an annotated commit, which lets you specify which extended sha syntax string was specified by a user, allowing for more exact reflog messages.
diff --git a/types/nodegit/revert.d.ts b/types/nodegit/revert.d.ts
index 1f9d4a2677..df804cbb48 100644
--- a/types/nodegit/revert.d.ts
+++ b/types/nodegit/revert.d.ts
@@ -13,7 +13,7 @@ export interface RevertOptions {
 }
 
 export class Revert {
-    static revert(repo: Repository, commit: Commit, givenOpts: RevertOptions): Promise<number>;
+    static revert(repo: Repository, commit: Commit, givenOpts?: RevertOptions): Promise<number>;
     /**
      * Reverts the given commit against the given "our" commit, producing an index that reflects the result of the revert.
      */