diff --git a/gruntjs/gruntjs-tests.ts b/gruntjs/gruntjs-tests.ts
index f36b74d76..853cac370 100644
--- a/gruntjs/gruntjs-tests.ts
+++ b/gruntjs/gruntjs-tests.ts
@@ -42,9 +42,20 @@ exports = (grunt: IGrunt) => {
         var valid = false;
         valid = valid && options.sourceRoot === "default";
         valid = valid && currenttask.data.repeat > 0;
-        return valid;
+
+        var done = this.async();
+        done();
     });
 
+    grunt.registerMultiTask('task-1', "", function() {
+        var done = this.async();
+        done(new Error('nope'));
+    });
+
+    grunt.registerMultiTask('task-2', "", function() {
+        var done = this.async();
+        done(false);
+    });
 
     // util methods
     var testOneArg = (a: number) => a * 2;
@@ -61,4 +72,4 @@ exports = (grunt: IGrunt) => {
     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 f601ce4fb..cfe2825e4 100644
--- a/gruntjs/gruntjs.d.ts
+++ b/gruntjs/gruntjs.d.ts
@@ -816,9 +816,10 @@ declare module grunt {
              * Either false or an Error object may be passed to the done function
              * to instruct Grunt that the task has failed.
              */
-            done(success: boolean): void;
-            done(error: Error): void;
-            done(result: any): void;
+            (success: boolean): void;
+            (error: Error): void;
+            (result: any): void;
+            (): void;
         }
 
         /**