diff --git a/tests/qunit/index.html b/tests/qunit/index.html
index b873811812..13cea269e5 100644
--- a/tests/qunit/index.html
+++ b/tests/qunit/index.html
@@ -5,6 +5,7 @@
 
   <!-- Dependencies -->
   <script src="../../src/wp-includes/js/jquery/jquery.js"></script>
+  <script src="../../src/wp-includes/js/jquery/ui/core.js"></script>
   <script src="../../src/wp-includes/js/underscore.min.js"></script>
   <script src="../../src/wp-includes/js/backbone.min.js"></script>
   <script src="../../src/wp-includes/js/zxcvbn.min.js"></script>