diff --git a/types/angular/index.d.ts b/types/angular/index.d.ts
index d046974ab9..cbc24799ef 100644
--- a/types/angular/index.d.ts
+++ b/types/angular/index.d.ts
@@ -602,7 +602,7 @@ declare namespace angular {
     ///////////////////////////////////////////////////////////////////////////
     interface ITimeoutService {
         (delay?: number, invokeApply?: boolean): IPromise<void>;
-        <T>(fn: (...args: any[]) => T, delay?: number, invokeApply?: boolean, ...args: any[]): IPromise<T>;
+        <T>(fn: (...args: any[]) => T | IPromise<T>, delay?: number, invokeApply?: boolean, ...args: any[]): IPromise<T>;
         cancel(promise?: IPromise<any>): boolean;
     }