1 files changed, 4 insertions, 2 deletions
diff --git a/synapse/config/ratelimiting.py b/synapse/config/ratelimiting.py
index 3f3997f4e5..7a8d5851c4 100644
--- a/synapse/config/ratelimiting.py
+++ b/synapse/config/ratelimiting.py
@@ -12,7 +12,7 @@
 # See the License for the specific language governing permissions and
 # limitations under the License.
 
-from typing import Dict
+from typing import Dict, Optional
 
 from ._base import Config
 
@@ -21,8 +21,10 @@ class RateLimitConfig:
     def __init__(
         self,
         config: Dict[str, float],
-        defaults={"per_second": 0.17, "burst_count": 3.0},
+        defaults: Optional[Dict[str, float]] = None,
     ):
+        defaults = defaults or {"per_second": 0.17, "burst_count": 3.0}
+
         self.per_second = config.get("per_second", defaults["per_second"])
         self.burst_count = int(config.get("burst_count", defaults["burst_count"]))