$NetBSD$

--- lib/ASN1.y.orig	2016-04-04 16:53:28.000000000 +0000
+++ lib/ASN1.y
@@ -575,7 +575,7 @@ _asn1_yylex ()
 
       /* Is STRING a number? */
       for (k = 0; k < counter; k++)
-        if (!isdigit (string[k]))
+        if (!isdigit ((unsigned char)string[k]))
           break;
       if (k >= counter)
         {