diff --git a/google/auth/external_account_authorized_user.py b/google/auth/external_account_authorized_user.py
index 04a7f5b91..a2d4edf6f 100644
--- a/google/auth/external_account_authorized_user.py
+++ b/google/auth/external_account_authorized_user.py
@@ -222,12 +222,19 @@ def can_refresh(self):
             (self._refresh_token, self._token_url, self._client_id, self._client_secret)
         )
 
-    def get_project_id(self):
+    def get_project_id(self, request=None):
         """Retrieves the project ID corresponding to the workload identity or workforce pool.
         For workforce pool credentials, it returns the project ID corresponding to
         the workforce_pool_user_project.
 
         When not determinable, None is returned.
+
+        Args:
+            request (google.auth.transport.requests.Request): Request object.
+                Unused here, but passed from _default.default().
+
+        Return:
+          str: project ID is not determinable for this credential type so it returns None
         """
 
         return None
diff --git a/tests/test_external_account_authorized_user.py b/tests/test_external_account_authorized_user.py
index c97d087b3..db18450a8 100644
--- a/tests/test_external_account_authorized_user.py
+++ b/tests/test_external_account_authorized_user.py
@@ -424,7 +424,10 @@ def test_to_json_full_with_strip(self):
 
     def test_get_project_id(self):
         creds = self.make_credentials()
-        assert creds.get_project_id() is None
+        request = mock.create_autospec(transport.Request)
+
+        assert creds.get_project_id(request) is None
+        request.assert_not_called()
 
     def test_with_quota_project(self):
         creds = self.make_credentials(