diff --git a/src/vs/base/common/winjs.base.d.ts b/src/vs/base/common/winjs.base.d.ts
index 3dd01d954f7..c568d4d7b05 100644
--- a/src/vs/base/common/winjs.base.d.ts
+++ b/src/vs/base/common/winjs.base.d.ts
@@ -6,7 +6,7 @@
 
 export type ErrorCallback = (error: any) => void;
 
-export declare class Promise<T = any> {
+export class Promise<T = any> {
 	constructor(
 		executor: (
 			resolve: (value: T | PromiseLike<T>) => void,