Problem building port

[Bernt Hansson]

Hello list!

I'm trying to build brlcad from ports on
FreeBSD 9.3-PRERELEASE #1 r266465

I get as far as this

[ 96%] Building C object src/libtclcad/CMakeFiles/libtclcad.dir/tclcad.c.o
In file included from 
/usr/ports/cad/brlcad/work/brlcad-7.24.0/src/libtclcad/tclcad.c:32:
/usr/local/include/tk8.6/tk.h:21:3: error: #error Tk 8.6 must be 
compiled with tcl.h from Tcl 8.6 or better
*** [src/libtclcad/CMakeFiles/libtclcad.dir/tclcad.c.o] Error code 1
1 error
*** [src/libtclcad/CMakeFiles/libtclcad.dir/all] Error code 2
Linking C executable ../../bin/rttherm
[ 96%] Built target rttherm
1 error
*** [all] Error code 2
1 error
===> Compilation failed unexpectedly.
Try to set MAKE_JOBS_UNSAFE=yes and rebuild before reporting the failure to
the maintainer.
*** [do-build] Error code 1

Stop in /usr/ports/cad/brlcad.

I've deinstalled tcl and tk and rebuilt them but all the same,
build stops at the same place.

How to proceed?