diff --git a/src/vehicle_gui.cpp b/src/vehicle_gui.cpp
index b8c9321366..00c8f57834 100644
--- a/src/vehicle_gui.cpp
+++ b/src/vehicle_gui.cpp
@@ -807,7 +807,7 @@ static void DrawVehicleImage(const Vehicle *v, int x, int y, VehicleID selection
  * @param line_height      Height of a single item line.
  * @param r                Rectangle with edge positions of the matrix widget.
  */
-void BaseVehicleListWindow::DrawVehicleListItems(VehicleID selected_vehicle, int line_height, const Rect &r)
+void BaseVehicleListWindow::DrawVehicleListItems(VehicleID selected_vehicle, int line_height, const Rect &r) const
 {
 	int left = r.left + WD_MATRIX_LEFT;
 	int right = r.right - WD_MATRIX_RIGHT;
diff --git a/src/vehicle_gui_base.h b/src/vehicle_gui_base.h
index 4b7eb8fb38..7cad956872 100644
--- a/src/vehicle_gui_base.h
+++ b/src/vehicle_gui_base.h
@@ -37,7 +37,12 @@ struct BaseVehicleListWindow: public Window {
 		this->vehicles.SetSortFuncs(this->vehicle_sorter_funcs);
 	}
 
-	void DrawVehicleListItems(VehicleID selected_vehicle, int line_height, const Rect &r);
+	BaseVehicleListWindow() : Window()
+	{
+		this->vehicles.SetSortFuncs(this->vehicle_sorter_funcs);
+	}
+
+	void DrawVehicleListItems(VehicleID selected_vehicle, int line_height, const Rect &r) const;
 	void SortVehicleList();
 	void BuildVehicleList(Owner owner, uint16 index, uint16 window_type);
 };