diff --git a/aircraft.h b/aircraft.h
--- a/aircraft.h
+++ b/aircraft.h
@@ -21,5 +21,6 @@ static inline bool IsAircraftInHangarSto
 uint16 AircraftDefaultCargoCapacity(CargoID cid, EngineID engine_type);
 
 void CcCloneAircraft(bool success, TileIndex tile, uint32 p1, uint32 p2);
+inline void HandleAircraftEnterHangar(Vehicle *v);
 
 #endif /* AIRCRAFT_H */