diff --git a/Include/tupleobject.h b/Include/tupleobject.h
index 58479ee..a5ab733 100644
--- a/Include/tupleobject.h
+++ b/Include/tupleobject.h
@@ -44,6 +44,7 @@
 PyAPI_FUNC(PyObject *) PyTuple_GetSlice(PyObject *, Py_ssize_t, Py_ssize_t);
 PyAPI_FUNC(int) _PyTuple_Resize(PyObject **, Py_ssize_t);
 PyAPI_FUNC(PyObject *) PyTuple_Pack(Py_ssize_t, ...);
+PyAPI_FUNC(void) _PyTuple_MaybeUntrack(PyObject *);
 
 /* Macro, trading safety for speed */
 #define PyTuple_GET_ITEM(op, i) (((PyTupleObject *)(op))->ob_item[i])