diff --git a/drivers/block/null_blk/main.c b/drivers/block/null_blk/main.c
index 862a9420df52..8e24fb93324c 100644
--- a/drivers/block/null_blk/main.c
+++ b/drivers/block/null_blk/main.c
@@ -1743,8 +1743,8 @@ static int null_validate_conf(struct nullb_device *dev)
 		return -EINVAL;
 	}
 
-	dev->blocksize = round_down(dev->blocksize, 512);
-	dev->blocksize = clamp_t(unsigned int, dev->blocksize, 512, 4096);
+	if (blk_validate_block_size(dev->blocksize))
+		return -EINVAL;
 
 	if (dev->queue_mode == NULL_Q_MQ && dev->use_per_node_hctx) {
 		if (dev->submit_queues != nr_online_nodes)