diff --git a/synapse/storage/registration.py b/synapse/storage/registration.py
index 524b5eeab..6c5b29288 100644
--- a/synapse/storage/registration.py
+++ b/synapse/storage/registration.py
@@ -915,7 +915,7 @@ class RegistrationBackgroundUpdateStore(
         return 1
 
 
-class RegistrationStore(RegistrationWorkerStore, RegistrationBackgroundUpdateStore):
+class RegistrationStore(RegistrationBackgroundUpdateStore):
     def __init__(self, db_conn, hs):
         super(RegistrationStore, self).__init__(db_conn, hs)