diff --git a/src/backend/rewrite/rewriteManip.c b/src/backend/rewrite/rewriteManip.c
index 6d56b65a4b..38c3e4e225 100644
--- a/src/backend/rewrite/rewriteManip.c
+++ b/src/backend/rewrite/rewriteManip.c
@@ -794,12 +794,10 @@ ChangeVarNodes(Node *node, int rt_index, int new_index, int sublevels_up)
 }
 
 /*
- * Substitute newrelid for oldrelid in a Relid set
- *
+ * Remove oldrelid from a Relid set and replace it with newrelid in case it is
+ * not a special varno.
  * Note: some extensions may pass a special varno such as INDEX_VAR for
  * oldrelid.  bms_is_member won't like that, but we should tolerate it.
- * (Perhaps newrelid could also be a special varno, but there had better
- * not be a reason to inject that into a nullingrels or phrels set.)
  */
 Relids
 adjust_relid_set(Relids relids, int oldrelid, int newrelid)