Automakers in Britain have sparked some Brexit contingency plans like certifying models in Europe and are now working on redrawing production schedules and stockpiling more parts to defend against any loss of unfettered trade following Brexit.

Such moves would enable plants, which rely on the just-in-time delivery of tens of thousands of components, to continue operating following the Brexit on March 29. However, it would add costs and bureaucracy that could risk their long term viability.

London and Brussels hope to agree a deal by the end of the year to sidestep tariffs and trade barriers, although Prime Minister Theresa May’s proposal have been criticized by the European Union and Brexiteers, who demand a cleaner break from the union.

McLaren Automotive, which manufactures around 5,000 cars per year at its English factory, is considering having its cars certified by both a British and European agency. It is also planning on stockpiling critical components and change when it sells into the European Union if there is some disruption.

“I will sell a little more in January and February and plan to pick the volume up in May and give us a leaner period through the change point,” Chief Executive Mike Flewitt said.