diff --git a/synapse/push/bulk_push_rule_evaluator.py b/synapse/push/bulk_push_rule_evaluator.py
index 5b1f9a1c2d..7f04d5668f 100644
--- a/synapse/push/bulk_push_rule_evaluator.py
+++ b/synapse/push/bulk_push_rule_evaluator.py
@@ -67,7 +67,7 @@ class BulkPushRuleEvaluator:
 
         defer.returnValue(rules_by_user)
 
-    @cached(max_entries=10000)
+    @cached()
     def _get_rules_for_room(self, room_id):
         """Get the current RulesForRoom object for the given room id