diff --git a/devtools/client/webconsole/test/test-bug-595934-workers.js b/devtools/client/webconsole/test/test-bug-595934-workers.js
index 37cef910dcd3..d23f080af2aa 100644
--- a/devtools/client/webconsole/test/test-bug-595934-workers.js
+++ b/devtools/client/webconsole/test/test-bug-595934-workers.js
@@ -3,7 +3,12 @@
 /* Any copyright is dedicated to the Public Domain.
  * http://creativecommons.org/publicdomain/zero/1.0/ */
 
-onmessage = function () {
+/* global fooBarWorker*/
+/* eslint-disable no-unused-vars*/
+
+"use strict";
+
+var onmessage = function () {
   fooBarWorker();
 };