diff --git a/app/index.html b/app/index.html
index 67e334f..0c81620 100644
--- a/app/index.html
+++ b/app/index.html
@@ -17,6 +17,8 @@
   <link rel="apple-touch-icon" href="../dev/images/favicon.png">
 
   <link rel="stylesheet" href="styles/index.scss">
+  <script crossorigin="anonymous"
+    src="https://polyfill.io/v3/polyfill.min.js?flags=gated&features=es2015%2Ces2016"></script>
   <script src="index.js"></script>
 </head>