According to a Financial Times report, Nikola founder Trevelor Milton purchased the original designs for his company’s flagship semi, the Nikola One, from a designer working at Rimac Automobili.

The hydrogen-powered Nikola One also happens to be at the center of a design patent infringement lawsuit, which Nikola filed against Tesla back in 2018. The former claimed that Tesla’s fully-electric Semi was “substantially” similar to its own design.

The report, which cites people with knowledge of the deal, states that Milton purchased the designs for several thousand dollars from Rimac’s Adriano Mudri, as per Autonews Europe.

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“The Nikola One truck was designed and patented by Nikola,” said the company in an official statement. “It is commonplace to license third party designs during vehicle development, and although early in the process Nikola purchased a license to Adriano Mudri’s designs, he was not part of the design team and his designs are materially different from the design invented by Nikola for the Nikola One.”

Tesla meanwhile has denied those design patent infringement charges in a filing last week, claiming that Adriano Mudri was the original designer of a hydrogen-powered concept truck dubbed ‘Road Runner’ and that Milton was aware of the concept before filing his own design patent application.

Following allegations of false claims about his company’s tech, Milton stepped down as chairman of Nikola last week, with Former GM exec Steve Girsky stepping in as his replacement.