diff --git a/drivers/mtd/ubi/fastmap.c b/drivers/mtd/ubi/fastmap.c
index 2a728c31e6b8..9a4940874be5 100644
--- a/drivers/mtd/ubi/fastmap.c
+++ b/drivers/mtd/ubi/fastmap.c
@@ -85,9 +85,10 @@ size_t ubi_calc_fm_size(struct ubi_device *ubi)
 		sizeof(struct ubi_fm_scan_pool) +
 		sizeof(struct ubi_fm_scan_pool) +
 		(ubi->peb_count * sizeof(struct ubi_fm_ec)) +
-		(sizeof(struct ubi_fm_eba) +
-		(ubi->peb_count * sizeof(__be32))) +
-		sizeof(struct ubi_fm_volhdr) * UBI_MAX_VOLUMES;
+		((sizeof(struct ubi_fm_eba) +
+		  sizeof(struct ubi_fm_volhdr)) *
+		 (UBI_MAX_VOLUMES + UBI_INT_VOL_COUNT)) +
+		(ubi->peb_count * sizeof(__be32));
 	return roundup(size, ubi->leb_size);
 }