diff -burN tcsh-6.20.00.orig/tw.parse.c tcsh-6.20.00/tw.parse.c

--- tcsh-6.20.00.orig/tw.parse.c	2015-10-16 17:59:56.000000000 +0300

+++ tcsh-6.20.00/tw.parse.c	2017-07-20 11:44:02.741303110 +0300

@@ -2173,6 +2173,8 @@

 	     (Strchr(val, 'x') != NULL);

     for (i = 0; i < count; i++)	{ /* find widest string */

+	/* check before converting to uint */

+	if (NLSStringWidth(items[i]) > 0)

 	maxwidth = max(maxwidth, (unsigned int) NLSStringWidth(items[i]));

     }