diff --git a/src/widgets/road_widget.h b/src/widgets/road_widget.h
--- a/src/widgets/road_widget.h
+++ b/src/widgets/road_widget.h
@@ -11,7 +11,7 @@
 #define WIDGETS_ROAD_WIDGET_H
 
 /** Widgets of the #BuildRoadToolbarWindow class. */
-enum RoadToolbarWidgets {
+enum RoadToolbarWidgets : WidgetID {
 	/* Name starts with RO instead of R, because of collision with RailToolbarWidgets */
 	WID_ROT_CAPTION,        ///< Caption of the window
 	WID_ROT_ROAD_X,         ///< Build road in x-direction.
@@ -31,7 +31,7 @@ enum RoadToolbarWidgets {
 };
 
 /** Widgets of the #BuildRoadDepotWindow class. */
-enum BuildRoadDepotWidgets {
+enum BuildRoadDepotWidgets : WidgetID {
 	/* Name starts with BRO instead of BR, because of collision with BuildRailDepotWidgets */
 	WID_BROD_CAPTION,   ///< Caption of the window.
 	WID_BROD_DEPOT_NE,  ///< Depot with NE entry.
@@ -41,7 +41,7 @@ enum BuildRoadDepotWidgets {
 };
 
 /** Widgets of the #BuildRoadStationWindow class. */
-enum BuildRoadStationWidgets {
+enum BuildRoadStationWidgets : WidgetID {
 	/* Name starts with BRO instead of BR, because of collision with BuildRailStationWidgets */
 	WID_BROS_CAPTION,                ///< Caption of the window.
 	WID_BROS_STATION_NE,             ///< Terminal station with NE entry.