diff --git a/test/index.html b/test/index.html
index 1f681ff..4690798 100644
--- a/test/index.html
+++ b/test/index.html
@@ -7,6 +7,7 @@
     <meta name="viewport" content="width=device-width, initial-scale=1">
     <link rel="stylesheet" type="text/css" media="screen" href="main.css" />
     <link href="https://fonts.googleapis.com/css?family=Roboto:300,400,500,700,400italic|Roboto+Mono:400,500|Material+Icons" rel="stylesheet">
+    <script src="https://cdnjs.cloudflare.com/polyfill/v3/polyfill.min.js"></script>
 </head>
 <body>
     <header class="header">
diff --git a/test/test-case-inactive.html b/test/test-case-inactive.html
index 7dcad8f..d2cfeed 100644
--- a/test/test-case-inactive.html
+++ b/test/test-case-inactive.html
@@ -7,6 +7,7 @@
     <meta name="viewport" content="width=device-width, initial-scale=1">
     <link rel="stylesheet" type="text/css" media="screen" href="main.css" />
     <link href="https://fonts.googleapis.com/css?family=Roboto:300,400,500,700,400italic|Roboto+Mono:400,500|Material+Icons" rel="stylesheet">
+    <script src="https://cdnjs.cloudflare.com/polyfill/v3/polyfill.min.js"></script>
 </head>
 <body>
     <header class="header">
