diff --git a/ChangeLog b/ChangeLog
index 724b1c3ba..2427e107e 100644
--- a/ChangeLog
+++ b/ChangeLog
@@ -1,5 +1,8 @@
 2009-05-08  Pavel Roskin  <proski@gnu.org>
 
+	* disk/raid.c (grub_raid_block_xor): Make buf2 constant, it's
+	not modified.
+
 	* disk/raid6_recover.c (grub_raid6_recover): Fix warnings about
 	uninitialized err[0] and err[1].  Rename them to bad1 and bad2.
 	Initialize them with -1.  Add sanity check for bad1.  Eliminate
diff --git a/disk/raid.c b/disk/raid.c
index 5cb412bf9..aac0f331a 100644
--- a/disk/raid.c
+++ b/disk/raid.c
@@ -172,12 +172,13 @@ grub_raid_close (grub_disk_t disk __attribute ((unused)))
 }
 
 void
-grub_raid_block_xor (char *buf1, char *buf2, int size)
+grub_raid_block_xor (char *buf1, const char *buf2, int size)
 {
-  grub_size_t *p1, *p2;
+  grub_size_t *p1;
+  const grub_size_t *p2;
 
   p1 = (grub_size_t *) buf1;
-  p2 = (grub_size_t *) buf2;
+  p2 = (const grub_size_t *) buf2;
   size /= GRUB_CPU_SIZEOF_VOID_P;
 
   while (size)
diff --git a/include/grub/raid.h b/include/grub/raid.h
index a36be6d95..595ced1d6 100644
--- a/include/grub/raid.h
+++ b/include/grub/raid.h
@@ -68,7 +68,7 @@ void grub_raid_register (grub_raid_t raid);
 void grub_raid_unregister (grub_raid_t raid);
 
 void grub_raid_rescan (void);
-void grub_raid_block_xor (char *buf1, char *buf2, int size);
+void grub_raid_block_xor (char *buf1, const char *buf2, int size);
 
 typedef grub_err_t (*grub_raid5_recover_func_t) (struct grub_raid_array *array,
                                                  int disknr, char *buf,