Apple Mac users booking hotels on the Orbitz travel site could end up paying more for their holidays, reports the Wall Street Journal.
Orbitz told the paper it was showing Mac users different, and in many cases more expensive, hotels to those shown to people browsing on a Windows PC.
Orbitz said research suggested Mac users generally spent about 30% more per night on hotels than PC users.
But it never showed the two user groups the same room for different prices.
Orbitz defended its policy as an "experiment" and said tools on its site let users customise what they saw in a way that would eliminate the differences.
"Nonsense that we'd charge Mac users more for the same hotel, which is unfortunately the incorrect impression that many readers seem to be drawing," said Orbitz chief executive Barney Harford.
"However, just as Mac users are willing to pay more for higher end computers, at Orbitz we've seen that Mac users are 40% more likely to book 4 or 5-star hotels as compared to PC users, and that's just one of many factors that determine which hotels to recommend a given customer as part of our efforts to show customers the most relevant hotels possible."
In addition the firm noted that when Mac and PC users visited the same hotel the Windows users tended to go for the cheaper rooms.
The average nightly spend on a hotel was $100 (£64), Orbitz said.
The company also owns the CheapTickets, ebookers, HotelClub and RatesToGo website.