diff --git a/block/bfq-iosched.c b/block/bfq-iosched.c
index 586fcfe..b200965 100644
--- a/block/bfq-iosched.c
+++ b/block/bfq-iosched.c
@@ -1924,12 +1924,13 @@ static void bfq_add_request(struct request *rq)
 		 * confirmed no later than during the next
 		 * I/O-plugging interval for bfqq.
 		 */
-		if (!bfq_bfqq_has_short_ttime(bfqq) &&
+		if (bfqd->last_completed_rq_bfqq &&
+		    !bfq_bfqq_has_short_ttime(bfqq) &&
 		    ktime_get_ns() - bfqd->last_completion <
 		    200 * NSEC_PER_USEC) {
 			if (bfqd->last_completed_rq_bfqq != bfqq &&
-				   bfqd->last_completed_rq_bfqq !=
-				   bfqq->waker_bfqq) {
+			    bfqd->last_completed_rq_bfqq !=
+			    bfqq->waker_bfqq) {
 				/*
 				 * First synchronization detected with
 				 * a candidate waker queue, or with a
@@ -4808,6 +4809,9 @@ void bfq_put_queue(struct bfq_queue *bfqq)
 			bfqq->bfqd->burst_size--;
 	}
 
+	if (bfqq->bfqd && bfqq->bfqd->last_completed_rq_bfqq == bfqq)
+		bfqq->bfqd->last_completed_rq_bfqq = NULL;
+
 	kmem_cache_free(bfq_pool, bfqq);
 #ifdef CONFIG_BFQ_GROUP_IOSCHED
 	bfqg_and_blkg_put(bfqg);