diff --git a/zerver/lib/actions.py b/zerver/lib/actions.py
index 7ad74aef59..67ce96ac85 100644
--- a/zerver/lib/actions.py
+++ b/zerver/lib/actions.py
@@ -939,10 +939,7 @@ def do_set_realm_notifications_stream(
 
 
 def do_set_realm_signup_notifications_stream(
-    realm: Realm,
-    stream: Optional[Stream],
-    stream_id: int,
-    acting_user: Optional[UserProfile] = None,
+    realm: Realm, stream: Optional[Stream], stream_id: int, *, acting_user: Optional[UserProfile]
 ) -> None:
     old_value = realm.signup_notifications_stream_id
     realm.signup_notifications_stream = stream
diff --git a/zerver/tests/test_events.py b/zerver/tests/test_events.py
index 2c80843135..982ec02f01 100644
--- a/zerver/tests/test_events.py
+++ b/zerver/tests/test_events.py
@@ -1172,6 +1172,7 @@ class NormalActionsTest(BaseAction):
                     self.user_profile.realm,
                     signup_notifications_stream,
                     signup_notifications_stream_id,
+                    acting_user=None,
                 )
             )
             check_realm_update("events[0]", events[0], "signup_notifications_stream_id")