small readability improvement

diff --git a/grub-core/disk/luks.c b/grub-core/disk/luks.c
index 4a35ef01174a6db867afb9e2d6af67b6c9cac7ec..a9590cab55bf0448d3e284b50124e4fea802f65b 100644 (file)
--- a/grub-core/disk/luks.c
+++ b/grub-core/disk/luks.c
@@ -637,7 +637,7 @@ luks_setkey (grub_luks_t dev, grub_uint8_t *key, grub_size_t keysize)
       grub_memset (idx, 0, GF_BYTES);
       for (i = 0; i < GRUB_DISK_SECTOR_SIZE; i += GF_BYTES)
        {
-         idx[15] = i / GF_BYTES;
+         idx[GF_BYTES - 1] = i / GF_BYTES;
          gf_mul_be (dev->lrw_precalc + i, idx, dev->lrw_key);
        }
     }