The Steam Packet Company's advising TT visitors to be careful about where they park in Liverpool.
It's after Merseyside Police revealed thieves had been targetting bikers as they travelled to the Pier Head to catch the ferry.
On Facebook, the company says it's aware of a couple of incidents in the UK where people have had their bikes stolen.
It says although the thefts didn't happen in the port areas, visitors should ensure their bikes and property are properly secured.