diff --git a/aio/src/app/custom-elements/elements-loader.spec.ts b/aio/src/app/custom-elements/elements-loader.spec.ts
index 3166db4118..58c9175908 100644
--- a/aio/src/app/custom-elements/elements-loader.spec.ts
+++ b/aio/src/app/custom-elements/elements-loader.spec.ts
@@ -39,7 +39,7 @@ describe('ElementsLoader', () => {
 
   // ElementsLoader uses the window's customElements API. Provide a fake for this test.
   beforeEach(() => {
-    fakeCustomElements = jasmine.createSpyObj('customElements', ['define']);
+    fakeCustomElements = jasmine.createSpyObj('customElements', ['define', 'whenDefined']);
     window.customElements = fakeCustomElements;
   });
   afterEach(() => {