diff --git a/include/wx/gtk/private.h b/include/wx/gtk/private.h
index 4bba0963a0..5ae45bd0c9 100644
--- a/include/wx/gtk/private.h
+++ b/include/wx/gtk/private.h
@@ -121,6 +121,7 @@ GtkWidget *GetButtonWidget();
 GtkWidget *GetCheckButtonWidget();
 GtkWidget *GetComboBoxWidget();
 GtkWidget *GetEntryWidget();
+GtkWidget *GetHeaderButtonWidgetFirst();
 GtkWidget *GetHeaderButtonWidget();
 GtkWidget *GetRadioButtonWidget();
 GtkWidget *GetSplitterWidget();