diff -r 3683d1a8c1c8 src/c/urweb.c
--- a/src/c/urweb.c	Sat Jun 15 08:18:47 2013 -0400
+++ b/src/c/urweb.c	Fri Jul 05 10:23:46 2013 +0600
@@ -2451,7 +2451,7 @@
       if (isprint((int)c))
         *s2++ = c;
       else if (uw_Estrings) {
-        sprintf(s2, "\\%03o", c);
+        sprintf(s2, "\\%03o", (unsigned char)c);
         s2 += 4;
       }
       else
@@ -2494,7 +2494,7 @@
     if (isprint((int)c))
       *s2++ = c;
     else if (uw_Estrings) {
-      sprintf(s2, "\\%03o", c);
+      sprintf(s2, "\\%03o", (unsigned char)c);
       s2 += 4;
     }
     else