diff --git a/d3-format/d3-format-tests.ts b/d3-format/d3-format-tests.ts
index 3fd5742997..57a98e26c6 100644
--- a/d3-format/d3-format-tests.ts
+++ b/d3-format/d3-format-tests.ts
@@ -63,11 +63,6 @@ num = d3Format.precisionRound(0.0005, 3000);
 // Test Locale Definition
 // ----------------------------------------------------------------------
 
-let decimal: '.' | ',' = localeDef.decimal;
-let thousands: '.' | ',' | '\u00a0' | "'" = localeDef.thousands;
-let grouping: Array<number> = localeDef.grouping;
-let currency: [string, string] = localeDef.currency;
-
 localeDef = {
     decimal: ',',
     thousands: '.',
@@ -75,6 +70,20 @@ localeDef = {
     currency: ['EUR', '']
 };
 
+localeDef = {
+  decimal: "\u066b",
+  thousands: "\u066c",
+  grouping: [3],
+  currency: ["", ""],
+  numerals : ["\u0660", "\u0661", "\u0662", "\u0663", "\u0664", "\u0665", "\u0666", "\u0667", "\u0668", "\u0669"]
+}
+
+let decimal: string = localeDef.decimal;
+let thousands: string = localeDef.thousands;
+let grouping: Array<number> = localeDef.grouping;
+let currency: [string, string] = localeDef.currency;
+let numerals: string[] | undefined = localeDef.numerals;
+
 localeObj = d3Format.formatLocale(localeDef);
 
 localeObj = d3Format.formatDefaultLocale(localeDef);
diff --git a/d3-format/index.d.ts b/d3-format/index.d.ts
index 92197f6ab8..be6c2b9a99 100644
--- a/d3-format/index.d.ts
+++ b/d3-format/index.d.ts
@@ -1,8 +1,10 @@
-// Type definitions for D3JS d3-format module v1.0.2
+// Type definitions for D3JS d3-format module 1.1
 // Project: https://github.com/d3/d3-format/
 // Definitions by: Tom Wanzek <https://github.com/tomwanzek>, Alex Ford <https://github.com/gustavderdrache>, Boris Yankov <https://github.com/borisyankov>
 // Definitions: https://github.com/DefinitelyTyped/DefinitelyTyped
 
+// Last module patch version validated against: 1.1.0
+
 /**
  * Specification of locale to use when creating a new FormatLocaleObject
  */
@@ -10,12 +12,12 @@ export interface FormatLocaleDefinition {
     /**
      * The decimal point (e.g., ".")
      */
-    decimal: '.' | ',';
+    decimal: string;
     /**
      * The group separator (e.g., ","). Note that the thousands property is a misnomer, as\
      * the grouping definition allows groups other than thousands.
      */
-    thousands: '.' | ',' | '\u00a0' | "'";
+    thousands: string;
     /**
      * The array of group sizes (e.g., [3]), cycled as needed.
      */
@@ -24,6 +26,10 @@ export interface FormatLocaleDefinition {
      * The currency prefix and suffix (e.g., ["$", ""])
      */
     currency: [string, string];
+    /**
+     * An array of ten strings to replace the numerals 0-9.
+     */
+    numerals?: string[];
 }
 
 /**