diff --git a/drivers/mtd/ubi/build.c b/drivers/mtd/ubi/build.c
index 7b1c332..b02880e 100644
--- a/drivers/mtd/ubi/build.c
+++ b/drivers/mtd/ubi/build.c
@@ -237,7 +237,11 @@
 	 * is that all the bad eraseblocks of the chip are in
 	 * the MTD partition we are attaching (ubi->mtd).
 	 */
-	device_size = ubi->mtd->size;
+	if (ubi->mtd->master)
+		device_size = ubi->mtd->master->size;
+	else
+		device_size = ubi->mtd->size;
+
 	device_pebs = mtd_div_by_eb(device_size, ubi->mtd);
 	limit = mult_frac(device_pebs, max_beb_per1024, 1024);