diff --git a/Include/pythonrun.h b/Include/pythonrun.h
index e0979b5..08278cf 100644
--- a/Include/pythonrun.h
+++ b/Include/pythonrun.h
@@ -69,6 +69,10 @@
 PyAPI_FUNC(void) PyErr_PrintEx(int);
 PyAPI_FUNC(void) PyErr_Display(PyObject *, PyObject *, PyObject *);
 
+/* Py_PyAtExit is for the atexit module, Py_AtExit is for low-level
+ * exit functions.
+ */
+PyAPI_FUNC(void) _Py_PyAtExit(void (*func)(void));
 PyAPI_FUNC(int) Py_AtExit(void (*func)(void));
 
 PyAPI_FUNC(void) Py_Exit(int);