diff --git a/Include/setobject.h b/Include/setobject.h
index 2739d62..fc32367 100644
--- a/Include/setobject.h
+++ b/Include/setobject.h
@@ -73,6 +73,8 @@
 	(Py_TYPE(ob) == &PySet_Type || Py_TYPE(ob) == &PyFrozenSet_Type || \
 	  PyType_IsSubtype(Py_TYPE(ob), &PySet_Type) || \
 	  PyType_IsSubtype(Py_TYPE(ob), &PyFrozenSet_Type))
+#define PySet_Check(ob) \
+	(Py_TYPE(ob) == &PySet_Type || PyType_IsSubtype(Py_TYPE(ob), &PySet_Type))
 
 PyAPI_FUNC(PyObject *) PySet_New(PyObject *);
 PyAPI_FUNC(PyObject *) PyFrozenSet_New(PyObject *);