osx compilation issues?

I'm attempting to build io on osx snow leopard, and running into an issue:

Linking C shared library ../../_build/dll/libbasekit.dylib
ld: duplicate symbol _List_size in CMakeFiles/basekit.dir/source/Stack.c.o and CMakeFiles/basekit.dir/source/List.c.o for architecture x86_64
collect2: ld returned 1 exit status
make[2]: *** [_build/dll/libbasekit.dylib] Error 1
make[1]: *** [libs/basekit/CMakeFiles/basekit.dir/all] Error 2

I get this same problem both from a git clone of the repo, as well as using a tarball from iolanguage.com. cmake did complain about a few things: GMP, FFI, GLFW, TIFF, but I'm not sure if any of these are show stoppers.

This is probably a problem specific to my system, but was hoping someone would have an idea about what this might be related to?  

thanks for your help, and looking forward to learning io!

--paul