diff --git a/synapse/storage/registration.py b/synapse/storage/registration.py
index c2efc3fd3..697d48712 100644
--- a/synapse/storage/registration.py
+++ b/synapse/storage/registration.py
@@ -156,9 +156,9 @@ class RegistrationStore(SQLBaseStore):
 
     def _all_users_on_domain_txn(self, txn, domain):
         sql = "SELECT COUNT(*) FROM users WHERE name NOT LIKE ?"
-        pat = "%:"+domain
+        pat = "%:" + domain
         cursor = txn.execute(sql, (pat,))
         num_not_matching = cursor.fetchall()[0][0]
         if num_not_matching == 0:
             return True
-        return False
\ No newline at end of file
+        return False