check_c_source_compiles(
            "
                /* OPENBSD WORKAROUND - DND*/
                #include <sys/types.h>
                /* OPENBSD WORKAROUND - END*/
                #include <sys/mman.h>
                int main(void)
                {
                    mmap((void *)0, 0, PROT_READ | PROT_WRITE, MAP_PRIVATE|MAP_ANON, -1, 0);
                    return 0;
                }
            "
            HAVE_MMAP_MAP_ANON
        )

elseif(NOT HAVE_MMAP_MAP_ANON AND NOT HAVE_MMAP_MAP_ANONYMOUS)