diff --git a/drivers/mtd/mtd_blkdevs.c b/drivers/mtd/mtd_blkdevs.c
index 44dc965a2f7c0d10d2f55245568274a59db0a1ff..cb47d79f4c2153092d712b82a03496bec601a17e 100644
--- a/drivers/mtd/mtd_blkdevs.c
+++ b/drivers/mtd/mtd_blkdevs.c
@@ -399,7 +399,7 @@ int add_mtd_blktrans_dev(struct mtd_blktrans_dev *new)
 		snprintf(gd->disk_name, sizeof(gd->disk_name),
 			 "%s%d", tr->name, new->devnum);
 
-	set_capacity(gd, (new->size * tr->blksize) >> 9);
+	set_capacity(gd, ((u64)new->size * tr->blksize) >> 9);
 
 	/* Create the request queue */
 	spin_lock_init(&new->queue_lock);