diff --git a/tests/oauth2/test_credentials.py b/tests/oauth2/test_credentials.py
index 78b1012..69d9fbc 100644
--- a/tests/oauth2/test_credentials.py
+++ b/tests/oauth2/test_credentials.py
@@ -454,6 +454,13 @@
         cred.refresh(None)
         assert cred.token == "access_token"
 
+    def test_with_quota_project(self):
+        cred = credentials.UserAccessTokenCredentials()
+        quota_project_cred = cred.with_quota_project("project-foo")
+
+        assert quota_project_cred._quota_project_id == "project-foo"
+        assert quota_project_cred._account == cred._account
+
     @mock.patch(
         "google.oauth2.credentials.UserAccessTokenCredentials.apply", autospec=True
     )
diff --git a/tests/oauth2/test_service_account.py b/tests/oauth2/test_service_account.py
index 457d472..7f27dad 100644
--- a/tests/oauth2/test_service_account.py
+++ b/tests/oauth2/test_service_account.py
@@ -291,6 +291,11 @@
         new_credentials = credentials.with_target_audience("https://new.example.com")
         assert new_credentials._target_audience == "https://new.example.com"
 
+    def test_with_quota_project(self):
+        credentials = self.make_credentials()
+        new_credentials = credentials.with_quota_project("project-foo")
+        assert new_credentials._quota_project_id == "project-foo"
+
     def test__make_authorization_grant_assertion(self):
         credentials = self.make_credentials()
         token = credentials._make_authorization_grant_assertion()