diff --git a/js/src/util.js b/js/src/util.js
index 14653c86e0..0ffbb76a3e 100644
--- a/js/src/util.js
+++ b/js/src/util.js
@@ -39,7 +39,7 @@ const Util = (($) => {
   }
 
   function transitionEndTest() {
-    if (window.QUnit) {
+    if (typeof window !== 'undefined' && window.QUnit) {
       return false
     }