diff --git a/src/backend/access/index/genam.c b/src/backend/access/index/genam.c
index 60a2b4e438..15debedf40 100644
--- a/src/backend/access/index/genam.c
+++ b/src/backend/access/index/genam.c
@@ -79,7 +79,7 @@ RelationGetIndexScan(Relation indexRelation, int nkeys, int norderbys)
 
 	scan->heapRelation = NULL;	/* may be set later */
 	scan->indexRelation = indexRelation;
-	scan->xs_snapshot = SnapshotNow;	/* may be set later */
+	scan->xs_snapshot = InvalidSnapshot;	/* caller must initialize this */
 	scan->numberOfKeys = nkeys;
 	scan->numberOfOrderBys = norderbys;
 
diff --git a/src/backend/executor/execUtils.c b/src/backend/executor/execUtils.c
index b449e0a553..39e3b2e79c 100644
--- a/src/backend/executor/execUtils.c
+++ b/src/backend/executor/execUtils.c
@@ -105,7 +105,7 @@ CreateExecutorState(void)
 	 * Initialize all fields of the Executor State structure
 	 */
 	estate->es_direction = ForwardScanDirection;
-	estate->es_snapshot = SnapshotNow;
+	estate->es_snapshot = InvalidSnapshot;	/* caller must initialize this */
 	estate->es_crosscheck_snapshot = InvalidSnapshot;	/* no crosscheck */
 	estate->es_range_table = NIL;
 	estate->es_plannedstmt = NULL;