diff --git a/packages/core/src/zone/ng_zone.ts b/packages/core/src/zone/ng_zone.ts
index 251eae4c9a..a8d5bb9d36 100644
--- a/packages/core/src/zone/ng_zone.ts
+++ b/packages/core/src/zone/ng_zone.ts
@@ -177,7 +177,7 @@ export class NgZone {
    * If a synchronous error happens it will be rethrown and not reported via `onError`.
    */
   run<T>(fn: (...args: any[]) => T, applyThis?: any, applyArgs?: any[]): T {
-    return (this as any as NgZonePrivate)._inner.run(fn, applyThis, applyArgs) as T;
+    return (this as any as NgZonePrivate)._inner.run(fn, applyThis, applyArgs);
   }
 
   /**
@@ -196,7 +196,7 @@ export class NgZone {
     const zone = (this as any as NgZonePrivate)._inner;
     const task = zone.scheduleEventTask('NgZoneEvent: ' + name, fn, EMPTY_PAYLOAD, noop, noop);
     try {
-      return zone.runTask(task, applyThis, applyArgs) as T;
+      return zone.runTask(task, applyThis, applyArgs);
     } finally {
       zone.cancelTask(task);
     }
@@ -207,7 +207,7 @@ export class NgZone {
    * rethrown.
    */
   runGuarded<T>(fn: (...args: any[]) => T, applyThis?: any, applyArgs?: any[]): T {
-    return (this as any as NgZonePrivate)._inner.runGuarded(fn, applyThis, applyArgs) as T;
+    return (this as any as NgZonePrivate)._inner.runGuarded(fn, applyThis, applyArgs);
   }
 
   /**
@@ -224,7 +224,7 @@ export class NgZone {
    * Use {@link #run} to reenter the Angular zone and do work that updates the application model.
    */
   runOutsideAngular<T>(fn: (...args: any[]) => T): T {
-    return (this as any as NgZonePrivate)._outer.run(fn) as T;
+    return (this as any as NgZonePrivate)._outer.run(fn);
   }
 }
 
@@ -388,19 +388,19 @@ export class NoopNgZone implements NgZone {
   readonly onStable: EventEmitter<any> = new EventEmitter();
   readonly onError: EventEmitter<any> = new EventEmitter();
 
-  run(fn: (...args: any[]) => any, applyThis?: any, applyArgs?: any): any {
+  run<T>(fn: (...args: any[]) => T, applyThis?: any, applyArgs?: any): T {
     return fn.apply(applyThis, applyArgs);
   }
 
-  runGuarded(fn: (...args: any[]) => any, applyThis?: any, applyArgs?: any): any {
+  runGuarded<T>(fn: (...args: any[]) => any, applyThis?: any, applyArgs?: any): T {
     return fn.apply(applyThis, applyArgs);
   }
 
-  runOutsideAngular(fn: (...args: any[]) => any): any {
+  runOutsideAngular<T>(fn: (...args: any[]) => T): T {
     return fn();
   }
 
-  runTask(fn: (...args: any[]) => any, applyThis?: any, applyArgs?: any, name?: string): any {
+  runTask<T>(fn: (...args: any[]) => T, applyThis?: any, applyArgs?: any, name?: string): T {
     return fn.apply(applyThis, applyArgs);
   }
 }
diff --git a/packages/zone.js/lib/zone.ts b/packages/zone.js/lib/zone.ts
index 7d6b3ebaff..54c188b5a7 100644
--- a/packages/zone.js/lib/zone.ts
+++ b/packages/zone.js/lib/zone.ts
@@ -223,9 +223,9 @@ interface Zone {
    * @param task to run
    * @param applyThis
    * @param applyArgs
-   * @returns {*}
+   * @returns {any} Value from the `task.callback` function.
    */
-  runTask(task: Task, applyThis?: any, applyArgs?: any): any;
+  runTask<T>(task: Task, applyThis?: any, applyArgs?: any): T;
 
   /**
    * Schedule a MicroTask.