diff --git a/block/blk-mq.c b/block/blk-mq.c
index 21cc7c2da0f9..6a789cda68a5 100644
--- a/block/blk-mq.c
+++ b/block/blk-mq.c
@@ -1262,6 +1262,7 @@ static void blk_add_rq_to_plug(struct blk_plug *plug, struct request *rq)
 		   (!blk_queue_nomerges(rq->q) &&
 		    blk_rq_bytes(last) >= BLK_PLUG_FLUSH_SIZE)) {
 		blk_mq_flush_plug_list(plug, false);
+		last = NULL;
 		trace_block_plug(rq->q);
 	}