diff --git a/Python/bltinmodule.c b/Python/bltinmodule.c
index 9adf530..291ef45 100644
--- a/Python/bltinmodule.c
+++ b/Python/bltinmodule.c
@@ -18,7 +18,7 @@
    Don't forget to modify PyUnicode_DecodeFSDefault() if you touch any of the
    values for Py_FileSystemDefaultEncoding!
 */
-#if defined(MS_WINDOWS) && defined(HAVE_USABLE_WCHAR_T)
+#ifdef HAVE_MBCS
 const char *Py_FileSystemDefaultEncoding = "mbcs";
 int Py_HasFileSystemDefaultEncoding = 1;
 #elif defined(__APPLE__)