the old CO_FUTURE flags can't be commented out
diff --git a/Include/pythonrun.h b/Include/pythonrun.h
index 86d9fe2..28e1690 100644
--- a/Include/pythonrun.h
+++ b/Include/pythonrun.h
@@ -7,7 +7,9 @@
extern "C" {
#endif
-#define PyCF_MASK CO_FUTURE_BARRY_AS_BDFL
+#define PyCF_MASK (CO_FUTURE_DIVISION | CO_FUTURE_ABSOLUTE_IMPORT | \
+ CO_FUTURE_WITH_STATEMENT | CO_FUTURE_PRINT_FUNCTION | \
+ CO_FUTURE_UNICODE_LITERALS | CO_FUTURE_BARRY_AS_BDFL)
#define PyCF_MASK_OBSOLETE 0
#define PyCF_SOURCE_IS_UTF8 0x0100
#define PyCF_DONT_IMPLY_DEDENT 0x0200