diff --git a/src/backend/catalog/index.c b/src/backend/catalog/index.c
index 1be27eec52..141632b748 100644
--- a/src/backend/catalog/index.c
+++ b/src/backend/catalog/index.c
@@ -3349,10 +3349,13 @@ index_set_state_flags(Oid indexId, IndexStateFlagsAction action)
 			 * CONCURRENTLY that failed partway through.)
 			 *
 			 * Note: the CLUSTER logic assumes that indisclustered cannot be
-			 * set on any invalid index, so clear that flag too.
+			 * set on any invalid index, so clear that flag too.  Similarly,
+			 * ALTER TABLE assumes that indisreplident cannot be set for
+			 * invalid indexes.
 			 */
 			indexForm->indisvalid = false;
 			indexForm->indisclustered = false;
+			indexForm->indisreplident = false;
 			break;
 		case INDEX_DROP_SET_DEAD:
 
@@ -3364,6 +3367,8 @@ index_set_state_flags(Oid indexId, IndexStateFlagsAction action)
 			 * the index at all.
 			 */
 			Assert(!indexForm->indisvalid);
+			Assert(!indexForm->indisclustered);
+			Assert(!indexForm->indisreplident);
 			indexForm->indisready = false;
 			indexForm->indislive = false;
 			break;