diff --git a/lib/internal/worker/io.js b/lib/internal/worker/io.js
index ad8056b5b9108a..9aa8c199588050 100644
--- a/lib/internal/worker/io.js
+++ b/lib/internal/worker/io.js
@@ -102,12 +102,6 @@ Object.defineProperty(MessagePort.prototype, onInitSymbol, {
 
 // This is called after the underlying `uv_async_t` has been closed.
 function onclose() {
-  if (typeof this.onclose === 'function') {
-    // Not part of the Web standard yet, but there aren't many reasonable
-    // alternatives in a non-EventEmitter usage setting.
-    // Refs: https://github.com/whatwg/html/issues/1766
-    this.onclose();
-  }
   this.emit('close');
 }