diff --git a/src/vehicle_type.h b/src/vehicle_type.h
--- a/src/vehicle_type.h
+++ b/src/vehicle_type.h
@@ -28,6 +28,8 @@ struct Train;
 struct RoadVehicle;
 struct Ship;
 struct Aircraft;
+struct EffectVehicle;
+struct DisasterVehicle;
 
 struct BaseVehicle
 {