diff --git a/src/settings_gui.cpp b/src/settings_gui.cpp
index 171a4fbd4b..5f00657b62 100644
--- a/src/settings_gui.cpp
+++ b/src/settings_gui.cpp
@@ -558,9 +558,9 @@ struct GameOptionsWindow : Window {
 				GfxClearSpriteCache();
 				_gui_zoom = (ZoomLevel)(ZOOM_LVL_OUT_4X - index);
 				switch (_gui_zoom) {
-					case ZOOM_LVL_NORMAL: ChangeResInGame(854, 480); break;
-					case ZOOM_LVL_OUT_2X: ChangeResInGame(1280, 720); break;
-					case ZOOM_LVL_OUT_4X: ChangeResInGame(1920, 1080); break;
+					case ZOOM_LVL_OUT_4X - ZOOM_LVL_NORMAL: ChangeResInGame(854, 480); break;
+					case ZOOM_LVL_OUT_4X - ZOOM_LVL_OUT_2X: ChangeResInGame(1280, 720); break;
+					case ZOOM_LVL_OUT_4X - ZOOM_LVL_OUT_4X: ChangeResInGame(1920, 1080); break;
 					default: break;
 				}
 				UpdateCursorSize();