diff --git a/README.md b/README.md
index 27d6be4e4a..8760adc871 100755
--- a/README.md
+++ b/README.md
@@ -86,7 +86,7 @@ List of Definitions
 * [GoJS](http://gojs.net/) (by [Barbara Duckworth](https://github.com/barbara42))
 * [Greasemonkey](http://www.greasespot.net/) (by [Kota Saito](https://github.com/kotas))
 * [GreenSock Animation Platform (GSAP)](http://www.greensock.com/get-started-js/) (by [Robert S.](https://github.com/codeBelt))
-* [Grunt JS](http://gruntjs.com/) (by [Jeff May](https://github.com/jeffmay) and [Basarat Ali Syed](https://github.com/basarat))
+* [Grunt JS](http://gruntjs.com/) (by [Jeff May](https://github.com/jeffmay), [Basarat Ali Syed](https://github.com/basarat) and [San Chen](https://github.com/bigsan))
 * [Google API Client](https://code.google.com/p/google-api-javascript-client/) (by [Frank M](https://github.com/sgtfrankieboy))
 * [Google App Engine Channel API](https://developers.google.com/appengine/docs/java/channel/javascript) (by [vvakame](https://github.com/vvakame))
 * [GoogleMaps](https://developers.google.com/maps/) (by [Esben Nepper](https://github.com/eNepper))
diff --git a/gruntjs/gruntjs-tests.ts b/gruntjs/gruntjs-tests.ts
index 84a5c22a4b..f36b74d764 100644
--- a/gruntjs/gruntjs-tests.ts
+++ b/gruntjs/gruntjs-tests.ts
@@ -57,4 +57,8 @@ exports = (grunt: IGrunt) => {
     asyncedTwoArgs(2, "values", (result: string) => {
         console.log(result);
     });
+    var fileMaps = grunt.file.expandMapping([''], '', { ext: '.js' });
+    fileMaps.length;
+    fileMaps[0].src.length;
+    fileMaps[0].dest;
 };
\ No newline at end of file
diff --git a/gruntjs/gruntjs.d.ts b/gruntjs/gruntjs.d.ts
index e676189101..99eadf435b 100644
--- a/gruntjs/gruntjs.d.ts
+++ b/gruntjs/gruntjs.d.ts
@@ -450,7 +450,7 @@ declare module grunt {
              * @see FileModule.expand method documentation for an explanation of how the patterns
              *      and options arguments may be specified.
              */
-            expandMapping(patterns: string[], dest: string, options: IExpandedFilesConfig): IFilesMap
+            expandMapping(patterns: string[], dest: string, options: IExpandedFilesConfig): Array<IFileMap>
 
             /**
              * Match one or more globbing patterns against one or more file paths.
@@ -558,7 +558,7 @@ declare module grunt {
             /**
              * Pattern(s) to match, relative to the {@link IExpandedFilesConfig.cwd}.
              */
-            src: string[]
+            src?: string[]
 
             /**
              * Destination path prefix.
@@ -599,7 +599,7 @@ declare module grunt {
             /**
              * Enables the following options
              */
-            expand: boolean // = true
+            expand?: boolean // = true
 
             /**
              * All {@link IExpandedFilesConfig.src} matches are relative to (but don't include) this path.
@@ -609,7 +609,7 @@ declare module grunt {
             /**
              * Replace any existing extension with this value in generated {@link IExpandedFilesConfig.dest} paths.
              */
-            ext?: boolean
+            ext?: string
 
             /**
              * Remove all path parts from generated {@link IExpandedFilesConfig.dest} paths.
@@ -622,17 +622,21 @@ declare module grunt {
              * and this function must return a new dest value.
              * If the same dest is returned more than once, each src which used it will be added to an array of sources for it.
              */
-            rename?: boolean
+            rename?: Function
         }
 
         /**
-         * @see {@link http://gruntjs.com/configuring-tasks#files-object-format}
+         * @see {@link http://gruntjs.com/configuring-tasks#files-array-format}
          */
-        interface IFilesMap {
+        interface IFileMap {
             /**
-             * A map of sources to a destination.
+             * source filenames.
              */
-            [dest: string]: string[]
+            src: string[]
+            /**
+             * destination filename.
+             */
+            dest: string
         }
     }
 
@@ -804,7 +808,7 @@ declare module grunt {
              * Normalizes a task target configuration object into an array of src-dest file mappings.
              * This method is used internally by the multi task system this.files / grunt.task.current.files property.
              */
-            normalizeMultiTaskFiles(data: grunt.config.IProjectConfig, targetname?: string): grunt.file.IFilesMap
+            normalizeMultiTaskFiles(data: grunt.config.IProjectConfig, targetname?: string): Array<grunt.file.IFileMap>
         }
 
         interface AsyncResultCatcher {