===================================================================
RCS file: /cvs/texi2mdoc/util.c,v
retrieving revision 1.15
retrieving revision 1.16
diff -u -p -r1.15 -r1.16
--- texi2mdoc/util.c	2015/02/25 14:49:14	1.15
+++ texi2mdoc/util.c	2015/02/25 15:50:56	1.16
@@ -1,4 +1,4 @@
-/*	$Id: util.c,v 1.15 2015/02/25 14:49:14 kristaps Exp $ */
+/*	$Id: util.c,v 1.16 2015/02/25 15:50:56 kristaps Exp $ */
 /*
  * Copyright (c) 2015 Kristaps Dzonsons <kristaps@bsd.lv>
  *
@@ -589,7 +589,7 @@ texicmd(struct texi *p, size_t pos, size_t *end, struc
 		return(TEXICMD__MAX);
 
 	/* Alphabetic commands are special. */
-	if ( ! isalpha(BUF(p)[pos])) {
+	if ( ! isalpha((unsigned char)BUF(p)[pos])) {
 		if ((*end = pos + 1) == BUFSZ(p))
 			return(TEXICMD__MAX);
 		for (i = 0; i < TEXICMD__MAX; i++) {