diff --git a/drivers/md/dm-verity-fec.c b/drivers/md/dm-verity-fec.c
index 85ad9dc210ff..c79f60df3a90 100644
--- a/drivers/md/dm-verity-fec.c
+++ b/drivers/md/dm-verity-fec.c
@@ -220,7 +220,7 @@ static int fec_read_bufs(struct dm_verity *v, struct dm_verity_io *io,
 				     PTR_ERR(bbuf));
 
 			/* assume the block is corrupted */
-			if (neras && *neras <= v->fec->roots)
+			if (neras && *neras < v->fec->roots)
 				fio->erasures[(*neras)++] = i;
 
 			continue;
@@ -238,7 +238,7 @@ static int fec_read_bufs(struct dm_verity *v, struct dm_verity_io *io,
 			 * skip if we have already found the theoretical
 			 * maximum number (i.e. fec->roots) of erasures
 			 */
-			if (neras && *neras <= v->fec->roots &&
+			if (neras && *neras < v->fec->roots &&
 			    fec_is_erasure(v, io, want_digest, bbuf))
 				fio->erasures[(*neras)++] = i;
 		}
diff --git a/drivers/md/dm-verity-fec.h b/drivers/md/dm-verity-fec.h
index 50b5e187d5cc..3885b514fc23 100644
--- a/drivers/md/dm-verity-fec.h
+++ b/drivers/md/dm-verity-fec.h
@@ -47,7 +47,7 @@ struct dm_verity_fec {
 /* per-bio data */
 struct dm_verity_fec_io {
 	struct rs_control *rs;	/* Reed-Solomon state */
-	int erasures[DM_VERITY_FEC_MAX_ROOTS + 1]; /* erasures for decode_rs8 */
+	int erasures[DM_VERITY_FEC_MAX_ROOTS]; /* erasures for decode_rs8 */
 	u8 *output;		/* buffer for corrected output */
 	unsigned int level;		/* recursion level */
 	unsigned int nbufs;		/* number of buffers allocated */