diff --git a/synapse/handlers/device.py b/synapse/handlers/device.py
index fcbe7f8e6b..8d630c6b1a 100644
--- a/synapse/handlers/device.py
+++ b/synapse/handlers/device.py
@@ -29,7 +29,7 @@ class DeviceHandler(BaseHandler):
 
     @defer.inlineCallbacks
     def check_device_registered(self, user_id, device_id,
-                                initial_device_display_name = None):
+                                initial_device_display_name=None):
         """
         If the given device has not been registered, register it with the
         supplied display name.