diff --git a/arithmetic_en.html b/arithmetic_en.html
index b347a487..fa581810 100644
--- a/arithmetic_en.html
+++ b/arithmetic_en.html
@@ -7,7 +7,7 @@
   <meta name="viewport" content="initial-scale=1,user-scalable=no,maximum-scale=1"/>
   <meta name="apple-mobile-web-app-capable" content="yes">
   <meta name="phet-sim-level" content="development">
-
+  
   <title>arithmetic</title>
 </head>
 
@@ -44,6 +44,7 @@
       '../sherpa/lib/game-up-camera-1.0.0.js', 
       '../sherpa/lib/base64-js-1.2.0.js', 
       '../sherpa/lib/TextEncoderLite-3c9f6f0.js', 
+      '../tandem/js/PhetioIDUtils.js', 
       '../sherpa/lib/Tween-r12.js'
     ];