diff --git a/src/rail_gui.cpp b/src/rail_gui.cpp
--- a/src/rail_gui.cpp
+++ b/src/rail_gui.cpp
@@ -862,7 +862,7 @@ static const WindowDesc _build_rail_desc
 	WDP_ALIGN_TBR, 22, 350, 36, 350, 36,
 	WC_BUILD_TOOLBAR, WC_NONE,
 	WDF_STD_TOOLTIPS | WDF_STD_BTN | WDF_DEF_WIDGET | WDF_STICKY_BUTTON | WDF_CONSTRUCTION,
-	NULL, _nested_build_rail_widgets, lengthof(_nested_build_rail_widgets)
+	_nested_build_rail_widgets, lengthof(_nested_build_rail_widgets)
 );
 
 
@@ -1472,7 +1472,7 @@ static const WindowDesc _station_builder
 	WDP_AUTO, WDP_AUTO, 148, 200, 148, 200,
 	WC_BUILD_STATION, WC_BUILD_TOOLBAR,
 	WDF_STD_TOOLTIPS | WDF_STD_BTN | WDF_DEF_WIDGET | WDF_CONSTRUCTION,
-	NULL, _nested_station_builder_widgets, lengthof(_nested_station_builder_widgets)
+	_nested_station_builder_widgets, lengthof(_nested_station_builder_widgets)
 );
 
 /** High level window description of the newGRF station-build window */
@@ -1480,7 +1480,7 @@ static const WindowDesc _newstation_buil
 	WDP_AUTO, WDP_AUTO, 148, 290, 148, 290,
 	WC_BUILD_STATION, WC_BUILD_TOOLBAR,
 	WDF_STD_TOOLTIPS | WDF_STD_BTN | WDF_DEF_WIDGET | WDF_CONSTRUCTION,
-	NULL, _nested_newstation_builder_widgets, lengthof(_nested_newstation_builder_widgets)
+	_nested_newstation_builder_widgets, lengthof(_nested_newstation_builder_widgets)
 );
 
 /** Open station build window */
@@ -1687,7 +1687,7 @@ static const WindowDesc _signal_builder_
 	WDP_AUTO, WDP_AUTO, 154, 68, 154, 68,
 	WC_BUILD_SIGNAL, WC_BUILD_TOOLBAR,
 	WDF_STD_TOOLTIPS | WDF_STD_BTN | WDF_DEF_WIDGET | WDF_UNCLICK_BUTTONS | WDF_CONSTRUCTION,
-	NULL, _nested_signal_builder_widgets, lengthof(_nested_signal_builder_widgets)
+	_nested_signal_builder_widgets, lengthof(_nested_signal_builder_widgets)
 );
 
 /**
@@ -1780,7 +1780,7 @@ static const WindowDesc _build_depot_des
 	WDP_AUTO, WDP_AUTO, 140, 122, 140, 122,
 	WC_BUILD_DEPOT, WC_BUILD_TOOLBAR,
 	WDF_STD_TOOLTIPS | WDF_STD_BTN | WDF_DEF_WIDGET | WDF_CONSTRUCTION,
-	NULL, _nested_build_depot_widgets, lengthof(_nested_build_depot_widgets)
+	_nested_build_depot_widgets, lengthof(_nested_build_depot_widgets)
 );
 
 static void ShowBuildTrainDepotPicker(Window *parent)
@@ -1882,7 +1882,7 @@ static const WindowDesc _build_waypoint_
 	WDP_AUTO, WDP_AUTO, 344, 92, 344, 92,
 	WC_BUILD_DEPOT, WC_BUILD_TOOLBAR,
 	WDF_STD_TOOLTIPS | WDF_STD_BTN | WDF_DEF_WIDGET | WDF_CONSTRUCTION,
-	NULL, _nested_build_waypoint_widgets, lengthof(_nested_build_waypoint_widgets)
+	_nested_build_waypoint_widgets, lengthof(_nested_build_waypoint_widgets)
 );
 
 static void ShowBuildWaypointPicker(Window *parent)