diff --git a/src/window_gui.h b/src/window_gui.h
--- a/src/window_gui.h
+++ b/src/window_gui.h
@@ -12,7 +12,6 @@
 #ifndef WINDOW_GUI_H
 #define WINDOW_GUI_H
 
-#include "core/math_func.hpp"
 #include "vehicle_type.h"
 #include "viewport_type.h"
 #include "company_type.h"