diff --git a/src/timetable_cmd.cpp b/src/timetable_cmd.cpp
--- a/src/timetable_cmd.cpp
+++ b/src/timetable_cmd.cpp
@@ -292,7 +292,7 @@ static bool VehicleTimetableSorter(Vehic
  * @param start_date The timetable start date.
  * @return The error or cost of the operation.
  */
-CommandCost CmdSetTimetableStart(DoCommandFlag flags, VehicleID veh_id, bool timetable_all, Date start_date)
+CommandCost CmdSetTimetableStart(DoCommandFlag flags, VehicleID veh_id, bool timetable_all, TimerGameCalendar::Date start_date)
 {
 	Vehicle *v = Vehicle::GetIfValid(veh_id);
 	if (v == nullptr || !v->IsPrimaryVehicle() || v->orders == nullptr) return CMD_ERROR;