Problem building htop

[Robin Becker]

I'm trying to build htop-0.8.1 from ports on a FreeBSD 6.1 system. It seems htop 
requires ncurses and I see this error

> In file included from RichString.h:14,
>                  from Object.h:12,
>                  from Process.h:14,
>                  from ProcessList.h:17,
>                  from Settings.h:13,
>                  from AvailableMetersPanel.h:6,
>                  from AvailableMetersPanel.c:2:
> /usr/include/curses.h:289: error: conflicting types for 'wchar_t'
> /usr/include/stdlib.h:58: error: previous declaration of 'wchar_t' was here
> *** Error code 1

do I need a more modern system or should I update the ports tree and try again? 
I guess that stdlib comes with the OS and maybe ncurses is modernized.
-- 
Robin Becker