Cython undefined symbol with c wrapper

I am trying to expose c code to cython and am running into "undefined symbol" errors when trying to use functions defined in my c file from another cython module.
Functions defined in my h files and functions using a manual wrapper work without a problem.

Basically the same case as this question but the solution (Linking against the library) isn't satisfactory for me.
I assume i am missing something in the setup.py script ?

foo.h

int source_func(void);

inline int header_func(void){
    return 1;
}

foo.c

#include "foo.h"

int source_func(void){
    return 2;
}

cdef extern from "foo.h":
    int source_func()
    int header_func()

cdef source_func_wrapper()

foo_wrapper.pyx

cdef source_func_wrapper():
    return source_func()

cimport foo_wrapper

def do_it():
    print "header func"
    print foo_wrapper.header_func() # ok
    print "source func wrapped"
    print foo_wrapper.source_func_wrapper() # ok    
    print "source func"
    print foo_wrapper.source_func() # undefined symbol: source_func

from distutils.core import setup
from distutils.extension import Extension
from Cython.Build import cythonize

# setup wrapper
setup(
    ext_modules = cythonize([
        Extension("foo_wrapper", ["foo_wrapper.pyx", "foo.c"])
    ])
)

# setup test module 
setup(
    ext_modules = cythonize([
        Extension("test_lib", ["test_lib.pyx"])
    ])
)