I got an undefined reference for scm_init_popen when I complied guile 2.0.6 on Windows, the scm_init_popen functions is introduced as following in the posix.c #ifdef HAVE_FORK static void scm_init_popen (void) { scm_c_define_gsubr ("open-process", 2, 0, 1, scm_open_process); } #endif since FORK is unavaiable in Windows, so the belowing part in posix.c should be error. scm_c_register_extension ("libguile-" SCM_EFFECTIVE_VERSION, "scm_init_popen", (scm_t_extension_init_func) scm_init_popen, NULL); Regards Ray Linn