diff --git a/synapse/replication/slave/storage/deviceinbox.py b/synapse/replication/slave/storage/deviceinbox.py

index 4d59778863..284fd30d89 100644
--- a/synapse/replication/slave/storage/deviceinbox.py
+++ b/synapse/replication/slave/storage/deviceinbox.py
@@ -24,15 +24,15 @@ class SlavedDeviceInboxStore(DeviceInboxWorkerStore, BaseSlavedStore):
     def __init__(self, db_conn, hs):
         super(SlavedDeviceInboxStore, self).__init__(db_conn, hs)
         self._device_inbox_id_gen = SlavedIdTracker(
-            db_conn, "device_max_stream_id", "stream_id",
+            db_conn, "device_max_stream_id", "stream_id"
         )
         self._device_inbox_stream_cache = StreamChangeCache(
             "DeviceInboxStreamChangeCache",
-            self._device_inbox_id_gen.get_current_token()
+            self._device_inbox_id_gen.get_current_token(),
         )
         self._device_federation_outbox_stream_cache = StreamChangeCache(
             "DeviceFederationOutboxStreamChangeCache",
-            self._device_inbox_id_gen.get_current_token()
+            self._device_inbox_id_gen.get_current_token(),
         )
 
         self._last_device_delete_cache = ExpiringCache(