diff --git a/tests/wpt/mozilla/tests/mozilla/bluetooth/requestDevice/canonicalizeFilter/no-arguments.html b/tests/wpt/mozilla/tests/mozilla/bluetooth/requestDevice/canonicalizeFilter/no-arguments.html
index 107614c557f..9713e748315 100644
--- a/tests/wpt/mozilla/tests/mozilla/bluetooth/requestDevice/canonicalizeFilter/no-arguments.html
+++ b/tests/wpt/mozilla/tests/mozilla/bluetooth/requestDevice/canonicalizeFilter/no-arguments.html
@@ -4,13 +4,8 @@
 <script src="/_mozilla/mozilla/bluetooth/bluetooth-helpers.js"></script>
 <script>
 'use strict';
-promise_test(() => {
+promise_test(t => {
     window.testRunner.setBluetoothMockDataSet(adapter_type.empty);
-    try {
-        window.navigator.bluetooth.requestDevice()
-        .then(() => assert_unreached('requestDevice() should have thrown an error'));
-    } catch(error) {
-        assert_equals('TypeError', error.name);
-    }
+    return promise_rejects(t, new TypeError(), window.navigator.bluetooth.requestDevice());
 }, 'requestDevice() requires an argument.');
 </script>
diff --git a/tests/wpt/mozilla/tests/mozilla/bluetooth/requestDevice/canonicalizeFilter/no-filters-member.html b/tests/wpt/mozilla/tests/mozilla/bluetooth/requestDevice/canonicalizeFilter/no-filters-member.html
index 7aa27067133..302a3072efb 100644
--- a/tests/wpt/mozilla/tests/mozilla/bluetooth/requestDevice/canonicalizeFilter/no-filters-member.html
+++ b/tests/wpt/mozilla/tests/mozilla/bluetooth/requestDevice/canonicalizeFilter/no-filters-member.html
@@ -4,13 +4,11 @@
 <script src="/_mozilla/mozilla/bluetooth/bluetooth-helpers.js"></script>
 <script>
 'use strict';
-promise_test(() => {
+promise_test(t => {
     window.testRunner.setBluetoothMockDataSet(adapter_type.empty);
-    try {
-        window.navigator.bluetooth.requestDevice([{}, {optionalServices: ['wrong_service']}])
-        .then(() => assert_unreached('requestDevice() should have thrown an error'));
-    } catch(error) {
-        assert_equals('TypeError', error.name);
-    }
+    return promise_rejects(
+        t,
+        new TypeError(),
+        window.navigator.bluetooth.requestDevice([{}, {optionalServices: ['wrong_service']}]));
 }, 'RequestDeviceOptions requires a |filters| member.');
 </script>
diff --git a/tests/wpt/mozilla/tests/mozilla/service-workers/service-worker-registration.html b/tests/wpt/mozilla/tests/mozilla/service-workers/service-worker-registration.html
index 291256c38b1..416c61806e1 100644
--- a/tests/wpt/mozilla/tests/mozilla/service-workers/service-worker-registration.html
+++ b/tests/wpt/mozilla/tests/mozilla/service-workers/service-worker-registration.html
@@ -36,7 +36,7 @@ promise_test(function() {
 }, "Test: Service Worker Registration property scope when provided a scope");
 
 promise_test(function (p) {
-  promise_rejects(p, new TypeError(), register_sw('./in%5Csome%5fdir/sw.js'));
+  return promise_rejects(p, new TypeError(), register_sw('./in%5Csome%5fdir/sw.js'));
 }, "Test: Throws Error when Invalid Url Path");
 
 promise_test(function (p) {