diff --git a/Include/object.h b/Include/object.h
index 1e92975..7f0e24a 100644
--- a/Include/object.h
+++ b/Include/object.h
@@ -438,6 +438,7 @@
 PyAPI_FUNC(int) PyObject_GenericSetAttr(PyObject *,
 					      PyObject *, PyObject *);
 PyAPI_FUNC(long) PyObject_Hash(PyObject *);
+PyAPI_FUNC(long) PyObject_HashNotImplemented(PyObject *);
 PyAPI_FUNC(int) PyObject_IsTrue(PyObject *);
 PyAPI_FUNC(int) PyObject_Not(PyObject *);
 PyAPI_FUNC(int) PyCallable_Check(PyObject *);