diff --git a/src/backend/access/heap/hio.c b/src/backend/access/heap/hio.c
index ccc4c6966a2..390db47d44e 100644
--- a/src/backend/access/heap/hio.c
+++ b/src/backend/access/heap/hio.c
@@ -404,7 +404,7 @@ RelationAddBlocks(Relation relation, BulkInsertState bistate,
 	{
 		BlockNumber first_fsm_block = first_block + not_in_fsm_pages;
 
-		FreeSpaceMapVacuumRange(relation, first_fsm_block, last_block);
+		FreeSpaceMapVacuumRange(relation, first_fsm_block, last_block + 1);
 	}
 
 	if (bistate)