Mark Object instances const
diff --git a/DisplayOptionsPanel.h b/DisplayOptionsPanel.h
index aad7bc7..02b67a0 100644
--- a/DisplayOptionsPanel.h
+++ b/DisplayOptionsPanel.h
@@ -18,7 +18,7 @@
    ScreenManager* scr;
 } DisplayOptionsPanel;
 
-extern PanelClass DisplayOptionsPanel_class;
+extern const PanelClass DisplayOptionsPanel_class;
 
 DisplayOptionsPanel* DisplayOptionsPanel_new(Settings* settings, ScreenManager* scr);