diff --git a/custom-event-polyfill.js b/custom-event-polyfill.js
index 851cabd..af302c4 100644
--- a/custom-event-polyfill.js
+++ b/custom-event-polyfill.js
@@ -5,7 +5,7 @@
 // https://developer.mozilla.org/en-US/docs/Web/API/CustomEvent#Polyfill
 
 try {
-    var ce = new window.CustomEvent('test');
+    var ce = new window.CustomEvent('test', {cancelable: true});
     ce.preventDefault();
     if (ce.defaultPrevented !== true) {
         // IE has problems with .preventDefault() on custom events