1 files changed, 1 insertions, 1 deletions
diff --git a/synapse/handlers/device.py b/synapse/handlers/device.py
index 46ee834407..35334725d7 100644
--- a/synapse/handlers/device.py
+++ b/synapse/handlers/device.py
@@ -267,7 +267,7 @@ class DeviceHandler(DeviceWorkerHandler):
 
         hs.get_distributor().observe("user_left_room", self.user_left_room)
 
-    def _check_device_name_length(self, name: Optional[str]):
+    def _check_device_name_length(self, name: Optional[str]) -> None:
         """
         Checks whether a device name is longer than the maximum allowed length.