diff --git a/src/backend/executor/nodeWindowAgg.c b/src/backend/executor/nodeWindowAgg.c
index e46a3dd1b7..4a5a6fbf07 100644
--- a/src/backend/executor/nodeWindowAgg.c
+++ b/src/backend/executor/nodeWindowAgg.c
@@ -4148,9 +4148,15 @@ int
 get_reduced_frame_map(WindowAggState *winstate, int64 pos)
 {
 	Assert(winstate->reduced_frame_map != NULL);
+	Assert(pos >= 0);
 
-	if (pos < 0 || pos >= winstate->alloc_sz)
-		elog(ERROR, "wrong pos: " INT64_FORMAT, pos);
+	/*
+	 * If pos is not in the reduced frame map, it means that any info
+	 * regarding the pos has not been registered yet. So we return
+	 * RF_NOT_DETERMINED.
+	 */
+	if (pos >= winstate->alloc_sz)
+		return RF_NOT_DETERMINED;
 
 	return winstate->reduced_frame_map[pos];
 }