diff --git a/dom/workers/test/test_webSocket_sharedWorker.html b/dom/workers/test/test_webSocket_sharedWorker.html
index 596a68c3ed60..9c0275961fcd 100644
--- a/dom/workers/test/test_webSocket_sharedWorker.html
+++ b/dom/workers/test/test_webSocket_sharedWorker.html
@@ -13,7 +13,8 @@
 
 <script class="testbody" type="text/javascript">
 
-SpecialPowers.pushPrefEnv({ set: [["dom.workers.sharedWorkers.enabled", true]] }, function() {
+SpecialPowers.pushPrefEnv({ set: [["dom.workers.sharedWorkers.enabled", true],
+                                  ["dom.workers.websocket.enabled", true]]}, function() {
   var sw = new SharedWorker('webSocket_sharedWorker.js');
   sw.port.onmessage = function(event) {
     if (event.data.type == 'finish') {