diff --git a/engine.c b/engine.c
--- a/engine.c
+++ b/engine.c
@@ -428,7 +428,7 @@ void EnginesMonthlyLoop(void)
 				CalcEngineReliability(e);
 			}
 
-			if (!(e->flags & ENGINE_AVAILABLE) && (uint16)(_date - min(_date, 365)) >= e->intro_date) {
+			if (!(e->flags & ENGINE_AVAILABLE) && _date >= (e->intro_date + 365)) {
 				// Introduce it to all players
 				NewVehicleAvailable(e);
 			} else if (!(e->flags & (ENGINE_AVAILABLE|ENGINE_INTRODUCING)) && _date >= e->intro_date) {
diff --git a/players.c b/players.c
--- a/players.c
+++ b/players.c
@@ -628,7 +628,7 @@ byte GetPlayerRailtypes(PlayerID p)
 		const EngineInfo *ei = &_engine_info[i];
 
 		if (e->type == VEH_Train && HASBIT(ei->climates, _opt.landscape) &&
-				(HASBIT(e->player_avail, p) || e->intro_date <= _date) &&
+				(HASBIT(e->player_avail, p) || _date >= (e->intro_date + 365)) &&
 				!(RailVehInfo(i)->flags & RVI_WAGON)) {
 			assert(e->railtype < RAILTYPE_END);
 			SETBIT(rt, e->railtype);