diff --git a/Mac/Include/pymactoolbox.h b/Mac/Include/pymactoolbox.h
index 99bf5ce4d1c..827a1462bd7 100644
--- a/Mac/Include/pymactoolbox.h
+++ b/Mac/Include/pymactoolbox.h
@@ -33,6 +33,7 @@ extern int CtlObj_Convert(PyObject *, ControlHandle *);
 extern PyObject *DlgObj_New(DialogPtr);
 extern int DlgObj_Convert(PyObject *, DialogPtr *);
 extern WindowPtr DlgObj_ConvertToWindow(PyObject *);
+extern PyObject *DlgObj_WhichDialog(DialogPtr);
 extern PyTypeObject Dialog_Type;
 #define DlgObj_Check(x) ((x)->ob_type == &Dialog_Type)