diff --git a/ChangeLog b/ChangeLog
index 21df4c53..661e9ca8 100644
--- a/ChangeLog
+++ b/ChangeLog
@@ -1,3 +1,8 @@
+2002-02-21  Guerrero, Juan Manuel  <st001906@hrz1.hrz.tu-darmstadt.de>
+
+	* src/getargs.c [AS_FILE_NAME] [__DJGPP__]: New macro STRLWR.
+	Check that no NULL pointer is passed to strlwr.
+
 2002-02-14  Paul Eggert  <eggert@twinsun.com>
 
 	Remove the support for C++ namespace cleanliness; it was
diff --git a/src/getargs.c b/src/getargs.c
index 02cfb845..0565b066 100644
--- a/src/getargs.c
+++ b/src/getargs.c
@@ -165,7 +165,8 @@ warranty; not even for MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE.\n\
 #ifdef MSDOS
 # if defined (__DJGPP__)
 /* Windows 9X and successors are case sensitive. */
-#  define AS_FILE_NAME(File) ((pathconf ((File), _PC_NAME_MAX) > 12) ? (File) : (strlwr (File), (File)))
+#  define STRLWR(String)     ((String) ? (strlwr (String), (String)) : (String))
+#  define AS_FILE_NAME(File) ((pathconf ((File), _PC_NAME_MAX) > 12) ? (File) : STRLWR (File))
 # else
 #  define AS_FILE_NAME(File) (strlwr (File), (File))
 # endif