Issue #11918: OS/2 and VMS are no more supported because of the lack of
maintainer.
diff --git a/Modules/main.c b/Modules/main.c
index 9137c85..747c12f 100644
--- a/Modules/main.c
+++ b/Modules/main.c
@@ -6,6 +6,7 @@
 #include <locale.h>
 
 #ifdef __VMS
+#error "PEP 11: VMS is now unsupported, code will be removed in Python 3.4"
 #include <unixlib.h>
 #endif