diff --git a/async/async.d.ts b/async/async.d.ts
index 475191aaf..adf6fe11b 100644
--- a/async/async.d.ts
+++ b/async/async.d.ts
@@ -96,7 +96,7 @@ interface Async {
     doWhilst(fn: AsyncVoidFunction, test: () => boolean, callback: (err: any) => void): void;
     until(test: () => boolean, fn: AsyncVoidFunction, callback: (err: any) => void): void;
     doUntil(fn: AsyncVoidFunction, test: () => boolean, callback: (err: any) => void): void;
-    waterfall(tasks: Function[], callback?: AsyncResultArrayCallback<any>): void;
+    waterfall(tasks: Function[], callback?: (err: any, ...arguments: any[]) => void): void;
     queue<T>(worker: AsyncWorker<T>, concurrency: number): AsyncQueue<T>;
     priorityQueue<T>(worker: AsyncWorker<T>, concurrency: number): AsyncPriorityQueue<T>;
     auto(tasks: any, callback?: AsyncResultArrayCallback<any>): void;