1 files changed, 4 insertions, 2 deletions
diff --git a/tests/util/test_ratelimitutils.py b/tests/util/test_ratelimitutils.py
index 4d1aee91d5..3fed55090a 100644
--- a/tests/util/test_ratelimitutils.py
+++ b/tests/util/test_ratelimitutils.py
@@ -12,6 +12,8 @@
 # WITHOUT WARRANTIES OR CONDITIONS OF ANY KIND, either express or implied.
 # See the License for the specific language governing permissions and
 # limitations under the License.
+from typing import Optional
+
 from synapse.config.homeserver import HomeServerConfig
 from synapse.util.ratelimitutils import FederationRateLimiter
 
@@ -89,9 +91,9 @@ def _await_resolution(reactor, d):
     return (reactor.seconds() - start_time) * 1000
 
 
-def build_rc_config(settings={}):
+def build_rc_config(settings: Optional[dict] = None):
     config_dict = default_config("test")
-    config_dict.update(settings)
+    config_dict.update(settings or {})
     config = HomeServerConfig()
     config.parse_config_dict(config_dict, "", "")
     return config.rc_federation