Close issue #6210: Implement PEP 409
diff --git a/Include/pyerrors.h b/Include/pyerrors.h
index 1bd0442..1e42ebb 100644
--- a/Include/pyerrors.h
+++ b/Include/pyerrors.h
@@ -105,6 +105,7 @@
/* Cause manipulation (PEP 3134) */
PyAPI_FUNC(PyObject *) PyException_GetCause(PyObject *);
PyAPI_FUNC(void) PyException_SetCause(PyObject *, PyObject *);
+PyAPI_FUNC(int) _PyException_SetCauseChecked(PyObject *, PyObject *);
/* Context manipulation (PEP 3134) */
PyAPI_FUNC(PyObject *) PyException_GetContext(PyObject *);