diff --git a/test/unit/sub/resolveurl-elements.html b/test/unit/sub/resolveurl-elements.html
index da180ee99e..b9bdfa82fb 100644
--- a/test/unit/sub/resolveurl-elements.html
+++ b/test/unit/sub/resolveurl-elements.html
@@ -34,31 +34,33 @@
   </template>
 </dom-module>
 <script>
-  class PR extends Polymer.Element {
-    static get is() { return 'p-r'; }
-  }
-  customElements.define(PR.is, PR);
+  window.addEventListener('WebComponentsReady', () => {
+    class PR extends Polymer.Element {
+      static get is() { return 'p-r'; }
+    }
+    customElements.define(PR.is, PR);
 
-  class PRImportMeta extends Polymer.Element {
-    static get template() {
-      return Polymer.DomModule.import('p-r', 'template').cloneNode(true);
+    class PRImportMeta extends Polymer.Element {
+      static get template() {
+        return Polymer.DomModule.import('p-r', 'template').cloneNode(true);
+      }
+      static get importMeta() {
+        // Idiomatically, this would be `return import.meta`, but for purposes
+        // of stubbing the test without actual modules, it's shimmed
+        return { url: 'http://class.com/mymodule/index.js' };
+      }
     }
-    static get importMeta() {
+    customElements.define('p-r-im', PRImportMeta);
+
+    const PRHybrid = Polymer({
+      is: 'p-r-hybrid',
+      _template: Polymer.DomModule.import('p-r', 'template').cloneNode(true),
       // Idiomatically, this would be `return import.meta`, but for purposes
       // of stubbing the test without actual modules, it's shimmed
-      return { url: 'http://class.com/mymodule/index.js' };
-    }
-  }
-  customElements.define('p-r-im', PRImportMeta);
+      importMeta: { url: 'http://hybrid.com/mymodule/index.js' }
+    });
 
-  const PRHybrid = Polymer({
-    is: 'p-r-hybrid',
-    _template: Polymer.DomModule.import('p-r', 'template').cloneNode(true),
-    // Idiomatically, this would be `return import.meta`, but for purposes
-    // of stubbing the test without actual modules, it's shimmed
-    importMeta: { url: 'http://hybrid.com/mymodule/index.js' }
   });
-
 </script>
 
 <dom-module id="p-r-ap" assetpath="../../assets/"></dom-module>