diff --git a/Include/object.h b/Include/object.h
index ab42f8a..30f0bec 100644
--- a/Include/object.h
+++ b/Include/object.h
@@ -379,6 +379,7 @@
 PyAPI_FUNC(int) PyObject_Compare(PyObject *, PyObject *);
 PyAPI_FUNC(PyObject *) PyObject_RichCompare(PyObject *, PyObject *, int);
 PyAPI_FUNC(int) PyObject_RichCompareBool(PyObject *, PyObject *, int);
+PyAPI_FUNC(PyObject *) Py_CmpToRich(int op, int cmp);
 PyAPI_FUNC(PyObject *) PyObject_GetAttrString(PyObject *, const char *);
 PyAPI_FUNC(int) PyObject_SetAttrString(PyObject *, const char *, PyObject *);
 PyAPI_FUNC(int) PyObject_HasAttrString(PyObject *, const char *);