diff --git a/test/test.browser.ts b/test/test.browser.ts
index 06df5af..e84a510 100644
--- a/test/test.browser.ts
+++ b/test/test.browser.ts
@@ -6,7 +6,7 @@ tap.test('should create a working button', async () => {
   const button: deesCatalog.DeesButton = await webhelpers.fixture(
     webhelpers.html`<dees-button></dees-button>`
   );
-  expect(button).to.be.instanceOf(deesCatalog.DeesButton);
+  expect(button).toBeInstanceOf(deesCatalog.DeesButton);
 });
 
 tap.start();