What used to be tp_xxx4 is now tp_flags; set it to Py_TPFLAGS_DEFAULT.
diff --git a/Modules/parsermodule.c b/Modules/parsermodule.c
index 8e9ca7e..33767b4 100644
--- a/Modules/parsermodule.c
+++ b/Modules/parsermodule.c
@@ -232,8 +232,7 @@
     /* Functions to access object as input/output buffer */
     0,					/* tp_as_buffer		*/
 
-    /* Space for future expansion */
-    0,					/* tp_xxx4		*/
+    Py_TPFLAGS_DEFAULT,			/* tp_flags		*/
 
     /* __doc__ */
     "Intermediate representation of a Python parse tree."