diff --git a/whatwg-streams/index.d.ts b/whatwg-streams/index.d.ts
index 45e33f40c3..79560b009a 100644
--- a/whatwg-streams/index.d.ts
+++ b/whatwg-streams/index.d.ts
@@ -95,7 +95,7 @@ declare class ReadableStreamBYOBRequest {
 
 interface WritableStreamSink {
     start?(controller: WritableStreamDefaultController): void | Promise<void>;
-    write?(chunk: any, controller: WritableStreamDefaultController): void | Promise<void>;
+    write?(chunk: any, controller?: WritableStreamDefaultController): void | Promise<any>;
     close?(controller: WritableStreamDefaultController): void | Promise<void>;
     abort?(reason: string): void | Promise<void>;
 }