diff --git a/ChangeLog b/ChangeLog
index 1f29e4b8b..a67f4596e 100644
--- a/ChangeLog
+++ b/ChangeLog
@@ -1,3 +1,9 @@
+2001-02-27  OKUJI Yoshinori  <okuji@gnu.org>
+
+	* stage2/builtins.c (chainloader_func): Don't check if the
+	current partition is FAT, but check if it has a FAT partition
+	type and the BPB has a system id starting with "MSWIN".
+	
 2001-02-27  OKUJI Yoshinori  <okuji@gnu.org>
 
 	Added hercules support based on a patch by Frank Mehnert
diff --git a/stage2/builtins.c b/stage2/builtins.c
index a47fc0320..02e236faf 100644
--- a/stage2/builtins.c
+++ b/stage2/builtins.c
@@ -448,12 +448,10 @@ chainloader_func (char *arg, int flags)
   grub_close ();
   kernel_type = KERNEL_TYPE_CHAINLOADER;
 
-  /* XXX: Windows evil hack. I don't know why, but Windows seems not to
-     set the start address of an extended partition in the BPB correctly.
-     So this is necessary to make Windows bootable even with an extended
-     partition. Maybe this should be made only for Windows, but how can
-     we determine if it is Windows or not precisely?!  */
-  if (open_partition () && fat_mount ())
+  /* XXX: Windows evil hack. For now, only the first five letters are
+     checked.  */
+  if (IS_PC_SLICE_TYPE_FAT (current_slice)
+      && ! grub_memcmp (BOOTSEC_LOCATION + BOOTSEC_BPB_SYSTEM_ID, "MSWIN", 5))
     *((unsigned long *) (BOOTSEC_LOCATION + BOOTSEC_BPB_HIDDEN_SECTORS))
       = part_start;
 
diff --git a/stage2/shared.h b/stage2/shared.h
index eac287a03..d6285b17a 100644
--- a/stage2/shared.h
+++ b/stage2/shared.h
@@ -175,6 +175,7 @@ extern char *grub_scratch_mem;
 #define BOOTSEC_SIGNATURE		0xAA55
 #define BOOTSEC_BPB_OFFSET		0x3
 #define BOOTSEC_BPB_LENGTH		0x3B
+#define BOOTSEC_BPB_SYSTEM_ID		0x3
 #define BOOTSEC_BPB_HIDDEN_SECTORS	0x1C
 #define BOOTSEC_PART_OFFSET		0x1BE
 #define BOOTSEC_PART_LENGTH		0x40