From 837ee038c5d8eb65cda7ca47c3185b348e7f7e08 Mon Sep 17 00:00:00 2001
From: Miles Bader <miles@gnu.org>
Date: Tue, 2 Jul 1996 16:25:58 +0000
Subject: [PATCH] (DRIVE_LETTER) [MSDOS]: Lower-case drive letters.

---
 src/fileio.c | 5 ++++-
 1 file changed, 4 insertions(+), 1 deletion(-)

diff --git a/src/fileio.c b/src/fileio.c
index 7df85fc78a1..9801948d356 100644
--- a/src/fileio.c
+++ b/src/fileio.c
@@ -102,7 +102,10 @@ extern char *strerror ();
    redirector allows the six letters between 'Z' and 'a' as well. */
 #ifdef MSDOS
 #define IS_DRIVE(x) ((x) >= 'A' && (x) <= 'z')
-#define DRIVE_LETTER(x) (x)
+/* Need to lower-case the drive letter, or else expanded
+   filenames will sometimes compare inequal, because
+   `expand-file-name' doesn't always down-case the drive letter.  */
+#define DRIVE_LETTER(x) (tolower (x))
 #endif
 #ifdef WINDOWSNT
 #define IS_DRIVE(x) isalpha (x)
-- 
2.39.2