diff --git a/drivers/mmc/card/block.c b/drivers/mmc/card/block.c
index 4409d79ed650..8e1a60e0818d 100644
--- a/drivers/mmc/card/block.c
+++ b/drivers/mmc/card/block.c
@@ -2147,7 +2147,7 @@ static struct mmc_blk_data *mmc_blk_alloc_req(struct mmc_card *card,
 	 */
 
 	snprintf(md->disk->disk_name, sizeof(md->disk->disk_name),
-		 "mmcblk%d%s", md->name_idx, subname ? subname : "");
+		 "mmcblk%u%s", md->name_idx, subname ? subname : "");
 
 	if (mmc_card_mmc(card))
 		blk_queue_logical_block_size(md->queue.queue,