diff --git a/roomserver/storage/postgres/events_table.go b/roomserver/storage/postgres/events_table.go
index ece1d9e3c..c136f039a 100644
--- a/roomserver/storage/postgres/events_table.go
+++ b/roomserver/storage/postgres/events_table.go
@@ -74,7 +74,7 @@ const insertEventSQL = "" +
 	"INSERT INTO roomserver_events AS e (room_nid, event_type_nid, event_state_key_nid, event_id, reference_sha256, auth_event_nids, depth, is_rejected)" +
 	" VALUES ($1, $2, $3, $4, $5, $6, $7, $8)" +
 	" ON CONFLICT ON CONSTRAINT roomserver_event_id_unique DO UPDATE" +
-	" SET is_rejected = $8 WHERE e.is_rejected = FALSE" +
+	" SET is_rejected = $8 WHERE e.event_id = $4 AND e.is_rejected = FALSE" +
 	" RETURNING event_nid, state_snapshot_nid"
 
 const selectEventSQL = "" +
@@ -192,7 +192,8 @@ func (s *eventStatements) InsertEvent(
 ) (types.EventNID, types.StateSnapshotNID, error) {
 	var eventNID int64
 	var stateNID int64
-	err := s.insertEventStmt.QueryRowContext(
+	stmt := sqlutil.TxStmt(txn, s.insertEventStmt)
+	err := stmt.QueryRowContext(
 		ctx, int64(roomNID), int64(eventTypeNID), int64(eventStateKeyNID),
 		eventID, referenceSHA256, eventNIDsAsArray(authEventNIDs), depth,
 		isRejected,