diff --git a/unix/gtkdlg.c b/unix/gtkdlg.c
index b18ef996..d4d0e828 100644
--- a/unix/gtkdlg.c
+++ b/unix/gtkdlg.c
@@ -2883,8 +2883,11 @@ void set_dialog_action_area(GtkDialog *dlg, GtkWidget *w)
                      w, FALSE, TRUE, 0);
     gtk_widget_show(w);
     gtk_widget_hide(gtk_dialog_get_action_area(dlg));
+#if !GTK_CHECK_VERSION(3,0,0)
+    /* This cosmetic property is withdrawn in GTK 3's GtkDialog */
     g_object_set(G_OBJECT(dlg), "has-separator", TRUE, (const char *)NULL);
 #endif
+#endif
 }
 
 int do_config_box(const char *title, Conf *conf, int midsession,