diff --git a/Include/abstract.h b/Include/abstract.h
index 6a6c94c..e9d1729 100644
--- a/Include/abstract.h
+++ b/Include/abstract.h
@@ -1233,6 +1233,13 @@
 PyAPI_FUNC(int) _PyObject_RealIsSubclass(PyObject *derived, PyObject *cls);
 
 
+/* For internal use by buffer API functions */
+PyAPI_FUNC(void) _Py_add_one_to_index_F(int nd, Py_ssize_t *index,
+                                        const Py_ssize_t *shape);
+PyAPI_FUNC(void) _Py_add_one_to_index_C(int nd, Py_ssize_t *index,
+                                        const Py_ssize_t *shape);
+
+
 #ifdef __cplusplus
 }
 #endif