diff --git a/block/mq-deadline.c b/block/mq-deadline.c
index f10c2a0d18d41..55e26065c2e27 100644
--- a/block/mq-deadline.c
+++ b/block/mq-deadline.c
@@ -622,8 +622,9 @@ static void dd_depth_updated(struct blk_mq_hw_ctx *hctx)
 	struct request_queue *q = hctx->queue;
 	struct deadline_data *dd = q->elevator->elevator_data;
 	struct blk_mq_tags *tags = hctx->sched_tags;
+	unsigned int shift = tags->bitmap_tags.sb.shift;
 
-	dd->async_depth = max(1UL, 3 * q->nr_requests / 4);
+	dd->async_depth = max(1U, 3 * (1U << shift)  / 4);
 
 	sbitmap_queue_min_shallow_depth(&tags->bitmap_tags, dd->async_depth);
 }