diff --git a/Include/iterobject.h b/Include/iterobject.h
index c078ebb..8e17d35 100644
--- a/Include/iterobject.h
+++ b/Include/iterobject.h
@@ -7,13 +7,13 @@
 
 PyAPI_DATA(PyTypeObject) PySeqIter_Type;
 
-#define PySeqIter_Check(op) ((op)->ob_type == &PySeqIter_Type)
+#define PySeqIter_Check(op) (Py_Type(op) == &PySeqIter_Type)
 
 PyAPI_FUNC(PyObject *) PySeqIter_New(PyObject *);
 
 PyAPI_DATA(PyTypeObject) PyCallIter_Type;
 
-#define PyCallIter_Check(op) ((op)->ob_type == &PyCallIter_Type)
+#define PyCallIter_Check(op) (Py_Type(op) == &PyCallIter_Type)
 
 PyAPI_FUNC(PyObject *) PyCallIter_New(PyObject *, PyObject *);
 #ifdef __cplusplus