diff --git a/src/backend/utils/sort/tuplesort.c b/src/backend/utils/sort/tuplesort.c
index 27069814de..b17347b214 100644
--- a/src/backend/utils/sort/tuplesort.c
+++ b/src/backend/utils/sort/tuplesort.c
@@ -4777,5 +4777,6 @@ free_sort_tuple(Tuplesortstate *state, SortTuple *stup)
 	{
 		FREEMEM(state, GetMemoryChunkSpace(stup->tuple));
 		pfree(stup->tuple);
+		stup->tuple = NULL;
 	}
 }