diff --git a/src/vs/base/common/async.ts b/src/vs/base/common/async.ts
index b1f1fbb14eb..aa4da71edc6 100644
--- a/src/vs/base/common/async.ts
+++ b/src/vs/base/common/async.ts
@@ -57,10 +57,10 @@ export function createCancelablePromise<T>(callback: (token: CancellationToken)
 		cancel() {
 			source.cancel();
 		}
-		then(resolve, reject) {
+		then<TResult1 = T, TResult2 = never>(resolve?: ((value: T) => TResult1 | Thenable<TResult1>) | undefined | null, reject?: ((reason: any) => TResult2 | Thenable<TResult2>) | undefined | null): Promise<TResult1 | TResult2> {
 			return promise.then(resolve, reject);
 		}
-		catch(reject) {
+		catch<TResult = never>(reject?: ((reason: any) => TResult | Thenable<TResult>) | undefined | null): Promise<T | TResult> {
 			return this.then(undefined, reject);
 		}
 	};