diff --git a/test/types/websocket.test-d.ts b/test/types/websocket.test-d.ts
new file mode 100644
index 00000000000..00a22f4e351
--- /dev/null
+++ b/test/types/websocket.test-d.ts
@@ -0,0 +1,10 @@
+import { ReadableStream, WritableStream } from 'stream/web'
+import { expectType } from 'tsd'
+import { WebSocketStream } from '../../types'
+
+declare const webSocketStream: WebSocketStream
+const webSocketStreamOpened = await webSocketStream.opened
+
+// Test that the readable and writable streams are of identical types to ones from stream/web
+expectType<WritableStream>(webSocketStreamOpened.writable)
+expectType<ReadableStream>(webSocketStreamOpened.readable)