===================================================================
RCS file: /cvsrepo/anoncvs/cvs/src/usr.bin/lex/scanopt.c,v
retrieving revision 1.3
retrieving revision 1.4
diff -u -r1.3 -r1.4
--- src/usr.bin/lex/scanopt.c	2015/11/19 23:34:56	1.3
+++ src/usr.bin/lex/scanopt.c	2015/11/20 00:05:02	1.4
@@ -1,4 +1,4 @@
-/* $OpenBSD: scanopt.c,v 1.3 2015/11/19 23:34:56 mmcc Exp $ */
+/* $OpenBSD: scanopt.c,v 1.4 2015/11/20 00:05:02 mmcc Exp $ */
 
 /* flex - tool to generate fast lexical analyzers */
 
@@ -48,7 +48,7 @@
      const char *a;
      const char *b;
 {
-	while (tolower (*a++) == tolower (*b++)) ;
+	while (tolower ((u_char)*a++) == tolower ((u_char)*b++)) ;
 	return b - a;
 }
 #endif