Ford Motor Co. has raised prices for two of its performance-car models in the U.K., citing tariffs stemming from the Brexit trade deal.

The base price of the Puma ST crossover is now 30,415 pounds ($41,600), the British magazine Autocar reported Tuesday, a roughly 6% increase from when the model was made available to order in September. The cost of the Fiesta ST also has gone up to as much as 28,770 pounds.

The models fall short of requirements established by the trade agreement between U.K. and European Union, according to a Ford spokesman. The accord’s rules-of-origin provisions require that gasoline- and diesel-powered cars have more than 55% of content coming from the country or bloc in order to qualify for tariff-free access. The Puma ST and Fiesta ST source their engines from the U.S.

The price increases went into effect in late December, just before the accord took effect Jan. 1. The hikes won’t significantly impact Ford’s overall sales, since regular versions of the Puma and Fiesta aren’t affected. ST iterations of the Fiesta were just 5% of deliveries last year, and the company will start handing over Puma ST to customers this quarter.