diff --git a/lib/internal/streams/destroy.js b/lib/internal/streams/destroy.js
index 200c75459ad56d..e59a61de1feef5 100644
--- a/lib/internal/streams/destroy.js
+++ b/lib/internal/streams/destroy.js
@@ -1,6 +1,7 @@
 'use strict';
 
-// Undocumented cb() API, needed for core, not for public API
+// Undocumented cb() API, needed for core, not for public API.
+// The cb() will be invoked synchronously if _destroy is synchronous.
 function destroy(err, cb) {
   const readableDestroyed = this._readableState &&
     this._readableState.destroyed;