diff --git a/src/station_cmd.cpp b/src/station_cmd.cpp
--- a/src/station_cmd.cpp
+++ b/src/station_cmd.cpp
@@ -3807,9 +3807,9 @@ void DeleteStaleLinks(Station *from)
 		for (Edge &edge : (*lg)[ge.node].edges) {
 			Station *to = Station::Get((*lg)[edge.dest_node].station);
 			assert(to->goods[c].node == edge.dest_node);
-			assert(_date >= edge.LastUpdate());
+			assert(TimerGameCalendar::date >= edge.LastUpdate());
 			uint timeout = LinkGraph::MIN_TIMEOUT_DISTANCE + (DistanceManhattan(from->xy, to->xy) >> 3);
-			if ((uint)(_date - edge.LastUpdate()) > timeout) {
+			if ((uint)(TimerGameCalendar::date - edge.LastUpdate()) > timeout) {
 				bool updated = false;
 
 				if (auto_distributed) {
@@ -3837,11 +3837,11 @@ void DeleteStaleLinks(Station *from)
 					while (iter != vehicles.end()) {
 						Vehicle *v = *iter;
 						/* Do not refresh links of vehicles that have been stopped in depot for a long time. */
-						if (!v->IsStoppedInDepot() || static_cast<uint>(_date - v->date_of_last_service) <=
+						if (!v->IsStoppedInDepot() || static_cast<uint>(TimerGameCalendar::date - v->date_of_last_service) <=
 								LinkGraph::STALE_LINK_DEPOT_TIMEOUT) {
 							LinkRefresher::Run(v, false); // Don't allow merging. Otherwise lg might get deleted.
 						}
-						if (edge.LastUpdate() == _date) {
+						if (edge.LastUpdate() == TimerGameCalendar::date) {
 							updated = true;
 							break;
 						}
@@ -3864,19 +3864,19 @@ void DeleteStaleLinks(Station *from)
 					ge.flows.DeleteFlows(to->index);
 					RerouteCargo(from, c, to->index, from->index);
 				}
-			} else if (edge.last_unrestricted_update != INVALID_DATE && (uint)(_date - edge.last_unrestricted_update) > timeout) {
+			} else if (edge.last_unrestricted_update != INVALID_DATE && (uint)(TimerGameCalendar::date - edge.last_unrestricted_update) > timeout) {
 				edge.Restrict();
 				ge.flows.RestrictFlows(to->index);
 				RerouteCargo(from, c, to->index, from->index);
-			} else if (edge.last_restricted_update != INVALID_DATE && (uint)(_date - edge.last_restricted_update) > timeout) {
+			} else if (edge.last_restricted_update != INVALID_DATE && (uint)(TimerGameCalendar::date - edge.last_restricted_update) > timeout) {
 				edge.Release();
 			}
 		}
 		/* Remove dead edges. */
 		for (NodeID r : to_remove) (*lg)[ge.node].RemoveEdge(r);
 
-		assert(_date >= lg->LastCompression());
-		if ((uint)(_date - lg->LastCompression()) > LinkGraph::COMPRESSION_INTERVAL) {
+		assert(TimerGameCalendar::date >= lg->LastCompression());
+		if ((uint)(TimerGameCalendar::date - lg->LastCompression()) > LinkGraph::COMPRESSION_INTERVAL) {
 			lg->Compress();
 		}
 	}
@@ -4304,7 +4304,7 @@ void BuildOilRig(TileIndex tile)
 	st->airport.Add(tile);
 	st->ship_station.Add(tile);
 	st->facilities = FACIL_AIRPORT | FACIL_DOCK;
-	st->build_date = _date;
+	st->build_date = TimerGameCalendar::date;
 	UpdateStationDockingTiles(st);
 
 	st->rect.BeforeAddTile(tile, StationRect::ADD_FORCE);