diff --git a/drivers/md/dm-verity-fec.c b/drivers/md/dm-verity-fec.c
index 98c7fd370056..93ecec407572 100644
--- a/drivers/md/dm-verity-fec.c
+++ b/drivers/md/dm-verity-fec.c
@@ -731,7 +731,8 @@ int verity_fec_ctr(struct dm_verity *v)
 	 * it to be large enough.
 	 */
 	f->hash_blocks = f->blocks - v->data_blocks;
-	if (dm_bufio_get_device_size(v->bufio) < f->hash_blocks) {
+	if (dm_bufio_get_device_size(v->bufio) <
+	    v->hash_start + f->hash_blocks) {
 		ti->error = "Hash device is too small for "
 			DM_VERITY_OPT_FEC_BLOCKS;
 		return -E2BIG;