diff --git a/Include/modsupport.h b/Include/modsupport.h
index c356f03e503..9b4d2b4d764 100644
--- a/Include/modsupport.h
+++ b/Include/modsupport.h
@@ -19,6 +19,18 @@ extern "C" {
 #define PyArg_VaParseTupleAndKeywords	_PyArg_VaParseTupleAndKeywords_SizeT
 #define PyArg_BuildValue		_PyArg_BuildValue_SizeT
 #define PyArg_VaBuildValue		_PyArg_VaBuildValue_SizeT
+#else
+#if HAVE_DECLSPEC_DLL
+PyAPI_FUNC(int) _PyArg_Parse_SizeT(PyObject *, char *, ...);
+PyAPI_FUNC(int) _PyArg_ParseTuple_SizeT(PyObject *, char *, ...);
+PyAPI_FUNC(int) _PyArg_ParseTupleAndKeywords_SizeT(PyObject *, PyObject *,
+                                                  const char *, char **, ...);
+PyAPI_FUNC(PyObject *) _Py_BuildValue_SizeT(const char *, ...);
+PyAPI_FUNC(int) _PyArg_VaParse_SizeT(PyObject *, char *, va_list);
+PyAPI_FUNC(int) _PyArg_VaParseTupleAndKeywords_SizeT(PyObject *, PyObject *,
+                                              const char *, char **, va_list);
+PyAPI_FUNC(PyObject *) _Py_VaBuildValue_SizeT(const char *, va_list);
+#endif
 #endif
 
 PyAPI_FUNC(int) PyArg_Parse(PyObject *, const char *, ...);