diff --git a/goldens/public-api/common/common.d.ts b/goldens/public-api/common/common.d.ts
index 55856b6199..f0daa116c8 100644
--- a/goldens/public-api/common/common.d.ts
+++ b/goldens/public-api/common/common.d.ts
@@ -3,10 +3,9 @@ export declare const APP_BASE_HREF: InjectionToken<string>;
 export declare class AsyncPipe implements OnDestroy, PipeTransform {
     constructor(_ref: ChangeDetectorRef);
     ngOnDestroy(): void;
-    transform<T>(obj: null): null;
-    transform<T>(obj: undefined): undefined;
-    transform<T>(obj: Observable<T> | null | undefined): T | null;
-    transform<T>(obj: Promise<T> | null | undefined): T | null;
+    transform<T>(obj: Observable<T> | Promise<T>): T | null;
+    transform<T>(obj: null | undefined): null;
+    transform<T>(obj: Observable<T> | Promise<T> | null | undefined): T | null;
 }
 
 export declare class CommonModule {
diff --git a/packages/common/src/pipes/async_pipe.ts b/packages/common/src/pipes/async_pipe.ts
index 3716d7db42..3921e1c018 100644
--- a/packages/common/src/pipes/async_pipe.ts
+++ b/packages/common/src/pipes/async_pipe.ts
@@ -94,11 +94,10 @@ export class AsyncPipe implements OnDestroy, PipeTransform {
     }
   }
 
-  transform<T>(obj: null): null;
-  transform<T>(obj: undefined): undefined;
-  transform<T>(obj: Observable<T>|null|undefined): T|null;
-  transform<T>(obj: Promise<T>|null|undefined): T|null;
-  transform(obj: Observable<any>|Promise<any>|null|undefined): any {
+  transform<T>(obj: Observable<T>|Promise<T>): T|null;
+  transform<T>(obj: null|undefined): null;
+  transform<T>(obj: Observable<T>|Promise<T>|null|undefined): T|null;
+  transform<T>(obj: Observable<T>|Promise<T>|null|undefined): T|null {
     if (!this._obj) {
       if (obj) {
         this._subscribe(obj);
@@ -108,7 +107,7 @@ export class AsyncPipe implements OnDestroy, PipeTransform {
 
     if (obj !== this._obj) {
       this._dispose();
-      return this.transform(obj as any);
+      return this.transform(obj);
     }
 
     return this._latestValue;
diff --git a/packages/common/test/pipes/async_pipe_spec.ts b/packages/common/test/pipes/async_pipe_spec.ts
index 42414897ea..00a2de5064 100644
--- a/packages/common/test/pipes/async_pipe_spec.ts
+++ b/packages/common/test/pipes/async_pipe_spec.ts
@@ -129,7 +129,7 @@ import {SpyChangeDetectorRef} from '../spies';
           reject = rej;
         });
         ref = new SpyChangeDetectorRef();
-        pipe = new AsyncPipe(<any>ref);
+        pipe = new AsyncPipe(ref as any);
       });
 
       describe('transform', () => {
@@ -218,10 +218,17 @@ import {SpyChangeDetectorRef} from '../spies';
       });
     });
 
+    describe('undefined', () => {
+      it('should return null when given undefined', () => {
+        const pipe = new AsyncPipe(null as any);
+        expect(pipe.transform(undefined)).toEqual(null);
+      });
+    });
+
     describe('other types', () => {
       it('should throw when given an invalid object', () => {
         const pipe = new AsyncPipe(null as any);
-        expect(() => pipe.transform(<any>'some bogus object')).toThrowError();
+        expect(() => pipe.transform('some bogus object' as any)).toThrowError();
       });
     });
   });
diff --git a/packages/language-service/test/definitions_spec.ts b/packages/language-service/test/definitions_spec.ts
index 0a3bed10e8..954736b8ce 100644
--- a/packages/language-service/test/definitions_spec.ts
+++ b/packages/language-service/test/definitions_spec.ts
@@ -251,7 +251,7 @@ describe('definitions', () => {
     expect(textSpan).toEqual(marker);
 
     expect(definitions).toBeDefined();
-    expect(definitions!.length).toBe(4);
+    expect(definitions!.length).toBe(3);
 
     const refFileName = '/node_modules/@angular/common/common.d.ts';
     for (const def of definitions!) {