diff --git a/src/settings_gui.cpp b/src/settings_gui.cpp
--- a/src/settings_gui.cpp
+++ b/src/settings_gui.cpp
@@ -460,8 +460,14 @@ struct GameOptionsWindow : Window {
 		}
 	}
 
-	virtual void OnInvalidateData(int data)
+	/**
+	 * Some data on this window has become invalid.
+	 * @param data Information about the changed data.
+	 * @param gui_scope Whether the call is done from GUI scope. You may not do everything when not in GUI scope. See #InvalidateWindowData() for details.
+	 */
+	virtual void OnInvalidateData(int data = 0, bool gui_scope = true)
 	{
+		if (!gui_scope) return;
 		this->SetWidgetLoweredState(GOW_FULLSCREEN_BUTTON, _fullscreen);
 
 		bool missing_files = BaseGraphics::GetUsedSet()->GetNumMissing() == 0;
@@ -724,8 +730,14 @@ public:
 		}
 	}
 
-	virtual void OnInvalidateData(int data = 0)
+	/**
+	 * Some data on this window has become invalid.
+	 * @param data Information about the changed data.
+	 * @param gui_scope Whether the call is done from GUI scope. You may not do everything when not in GUI scope. See #InvalidateWindowData() for details.
+	 */
+	virtual void OnInvalidateData(int data = 0, bool gui_scope = true)
 	{
+		if (!gui_scope) return;
 		uint i;
 		const SettingDesc *sd = GetSettingFromName("difficulty.max_no_competitors", &i);
 		for (i = 0; i < GAME_DIFFICULTY_NUM; i++, sd++) {