diff --git a/src/service/rooms/event_handler/upgrade_outlier_pdu.rs b/src/service/rooms/event_handler/upgrade_outlier_pdu.rs
index ae36edab9..d762baf40 100644
--- a/src/service/rooms/event_handler/upgrade_outlier_pdu.rs
+++ b/src/service/rooms/event_handler/upgrade_outlier_pdu.rs
@@ -388,7 +388,7 @@ pub(super) async fn upgrade_outlier_to_timeline_pdu<Pdu>(
 
 		// Event has passed all auth/stateres checks
 		drop(state_lock);
-		if incoming_pdu.depth > min_depth {
+		if incoming_pdu.depth > min_depth && incoming_pdu.state_key().is_some() {
 			self.services
 				.metadata
 				.set_mindepth(room_id, incoming_pdu.depth.into());