Sigh.  On Windows, (mode_t)i fails.  Assume that there's a prototype
in scope on systems where mode_t isn't the same size as int...
diff --git a/Modules/posixmodule.c b/Modules/posixmodule.c
index 8458d58..0ce2dfa 100644
--- a/Modules/posixmodule.c
+++ b/Modules/posixmodule.c
@@ -698,7 +698,7 @@
 	if (!PyArg_ParseTuple(args, "si", &path, &i))
 		return NULL;
 	Py_BEGIN_ALLOW_THREADS
-	res = chmod(path, (mode_t)i);
+	res = chmod(path, i);
 	Py_END_ALLOW_THREADS
 	if (res < 0)
 		return posix_error_with_filename(path);