diff --git a/gulp/gulp-tests.ts b/gulp/gulp-tests.ts
index 50ebeebf0..7e07f25f7 100644
--- a/gulp/gulp-tests.ts
+++ b/gulp/gulp-tests.ts
@@ -2,20 +2,28 @@
 
 import gulp = require("gulp");
 
-var typescript: any = null; // this would be the TypeScript compiler
-var jasmine: any = null; // this would be the jasmine test runner
+var typescript: IGulpPlugin = null; // this would be the TypeScript compiler
+var jasmine: IGulpPlugin = null; // this would be the jasmine test runner
 
 gulp.task('compile', function()
 {
     gulp.src("**/*.ts")
-        .pipe(typescript)
-        .dest('out')
+        .pipe(typescript())
+        .pipe(gulp.dest('out'))
 });
 
-gulp.task('test', ['compile'], function()
+gulp.task('compile2', function(callback: (err?: any) => void)
+{
+    gulp.src("**/*.ts")
+        .pipe(typescript())
+        .pipe(gulp.dest('out'))
+        .on('end', callback);
+});
+
+gulp.task('test', ['compile', 'compile2'], function()
 {
     gulp.src("out/test/**/*.js")
-        .pipe(jasmine);
+        .pipe(jasmine());
 });
 
 gulp.task('default', ['compile', 'test']);
diff --git a/gulp/gulp.d.ts b/gulp/gulp.d.ts
index d12c3edc1..7ec11def7 100644
--- a/gulp/gulp.d.ts
+++ b/gulp/gulp.d.ts
@@ -173,15 +173,10 @@ declare module gulp {
     interface ITaskCallback {
         /**
          * Defines a task.
-         * Tasks may be made asynchronous if they return a promise or a stream.
-         */
-        (): any;
-
-        /**
-         * Defines an asynchronous task.
+         * Tasks may be made asynchronous if they are passing a callback or return a promise or a stream.
          * @param cb callback used to signal asynchronous completion. Caller includes <code>err</code> in case of error.
          */
-        (cb:(err?:any)=>void): void;
+        (cb?:(err?:any)=>void): any;
     }
 
     interface EventEmitter {
@@ -287,3 +282,7 @@ declare module "gulp" {
     var _tmp:gulp.Gulp;
     export = _tmp;
 }
+
+interface IGulpPlugin {
+    (...args: any[]): NodeJS.ReadWriteStream;
+}