diff --git a/drivers/mtd/devices/block2mtd.c b/drivers/mtd/devices/block2mtd.c
index 03e80b2c4f5a..3e2367dfff88 100644
--- a/drivers/mtd/devices/block2mtd.c
+++ b/drivers/mtd/devices/block2mtd.c
@@ -293,7 +293,7 @@ static struct block2mtd_dev *add_device(char *devname, int erase_size,
 	}
 
 	size = bdev_nr_bytes(bdev);
-	if ((long)size % erase_size) {
+	if (!erase_size || size % erase_size) {
 		pr_err("erasesize must be a divisor of device size\n");
 		goto err_free_block2mtd;
 	}