_tkagg build error

I'm trying to build from cvs. It builds fine unless I try to build TkAgg:


building 'matplotlib.backends._tkagg' extension
gcc -pthread -fno-strict-aliasing -DNDEBUG -O2 -fomit-frame-pointer -pipe
-march=i586 -mcpu=pentiumpro -g -fPIC -I/usr/lib/tcl8.4/../../include
-I/usr/include -Isrc -Iagg2/include -I/usr/include -I/usr/include/freetype2
-I/usr/include/python2.3 -c src/_tkagg.cpp -o
src/_tkagg.cpp: In function `PyObject* _tkinit(PyObject*, PyObject*)':
src/_tkagg.cpp:134: error: invalid conversion from `int (*)(void*,
Tcl_Interp*, int, char**)' to `int (*)(void*, Tcl_Interp*, int, const
error: command 'gcc' failed with exit status 1

I'm on Mandrake 10.0 which uses gcc 3.3.2
I apologize if I've made some obvious omission.
I'm no c wizard (that's why I want matplotlib!).