diff --git a/modules/@angular/core/testing/testing.ts b/modules/@angular/core/testing/testing.ts
index c01693d550..85758b1d97 100644
--- a/modules/@angular/core/testing/testing.ts
+++ b/modules/@angular/core/testing/testing.ts
@@ -86,7 +86,7 @@ jsmBeforeEach(() => { testInjector.reset(); });
  *
  * {@example testing/ts/testing.ts region='beforeEachProviders'}
  */
-export function beforeEachProviders(fn): void {
+export function beforeEachProviders(fn: () => Array<any>): void {
   jsmBeforeEach(() => {
     var providers = fn();
     if (!providers) return;