diff --git a/test/index.html b/test/index.html
index 4f0da62ad0..9e79a0bb0a 100644
--- a/test/index.html
+++ b/test/index.html
@@ -15,7 +15,9 @@
   <script type="text/javascript" src="../node_modules/mocha/mocha.js"></script>
   <script type="text/javascript" src="../node_modules/proj4/dist/proj4.js"></script>
   <script type="text/javascript" src="test-extensions.js"></script>
-  <script src="https://cdn.polyfill.io/v2/polyfill.min.js?features=requestAnimationFrame,Element.prototype.classList,URL"></script>
+  <!-- load polyfills: Always load the URL polyfill in a gated form so that
+       MS Edge has it -->
+  <script src="https://cdn.polyfill.io/v2/polyfill.min.js?features=requestAnimationFrame,Element.prototype.classList,URL|always|gated"></script>
   <script>
     if (typeof initMochaPhantomJS === 'function') {
       initMochaPhantomJS()