diff --git a/block/blk-stat.c b/block/blk-stat.c
index ae3dd1fb8e61..6e602f9b966e 100644
--- a/block/blk-stat.c
+++ b/block/blk-stat.c
@@ -28,7 +28,7 @@ void blk_rq_stat_init(struct blk_rq_stat *stat)
 /* src is a per-cpu stat, mean isn't initialized */
 void blk_rq_stat_sum(struct blk_rq_stat *dst, struct blk_rq_stat *src)
 {
-	if (!src->nr_samples)
+	if (dst->nr_samples + src->nr_samples <= dst->nr_samples)
 		return;
 
 	dst->min = min(dst->min, src->min);