diff --git a/synapse/config/server.py b/synapse/config/server.py
index b5c2098ecb..9f15ed109e 100644
--- a/synapse/config/server.py
+++ b/synapse/config/server.py
@@ -542,7 +542,7 @@ class ServerConfig(Config):
 
         # Turn the list into a set to improve lookup speed.
         self.users_new_default_push_rules = set(
-            self.users_new_default_push_rules
+            users_new_default_push_rules
         )  # type: set
 
     def has_tls_listener(self) -> bool: