diff --git a/lib/_stream_writable.js b/lib/_stream_writable.js
index 19c0c8a006f62a..9c7e2630161cd9 100644
--- a/lib/_stream_writable.js
+++ b/lib/_stream_writable.js
@@ -1,5 +1,5 @@
 // A bit simpler than readable streams.
-// Implement an async ._write(chunk, cb), and it'll handle all
+// Implement an async ._write(chunk, encoding, cb), and it'll handle all
 // the drain event emission and buffering.
 
 'use strict';