The U.S. Patent and Trademark Office has rejected an attempt by Tesla to invalidate a design infringement lawsuit brought forward by Nikola Motor.

In May 2018, Nikola sued Tesla asserting that the design of the Tesla Semi closely resembled the design of the Nikola One. The truck startup specifically said the design infringed on the wraparound windshield, cab shape, and the design and position of the door which Nikola had patented. Nikola is seeking $2 billion in damages from Tesla, asserting that the design similarities diverted sales away from the hydrogen truck maker to Tesla.

Read More: Nikola Sues Tesla For Semi Patent Infringement, Seeks Damages Of More Than $2 Billion

Tesla filed a request with the Patent Trial and Appeal Board in September 2019 seeking a review to invalidate Nikola’s patent for its door design, Forbes reports.

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The Tesla Semi above, and Nikola Motors’ One truck below

“Tesla loses bid to invalidate @nikolamotor patents in USPTO dispute. USPTO not only upheld Nikola semi truck important patents but refused Tesla’s ask to modify our patents,” Nikola founder and chief executive Trevor Milton wrote in a since-deleted tweet. “Two billion dollar lawsuit moving forward. We will defend our company’s IP no matter who it is.”

Of course, this decision doesn’t directly impact the lawsuit but had Tesla’s appeal to overturn the door utility patent been successful, it would have weakened a key part of the lawsuit.

Since showcasing the Nikola One to the world back in 2016, the truck maker has racked up roughly 14,000 orders representing $10 billion of future revenue. In March it announced a $3.3 billion merger with VectoIQ, a publically-traded company established by former General Motors vice chair Steve Girsky. This merger included a $525 million capital raise from investors such as Fidelity and hedge fund ValueAct Capital.

Nikola Motor received $4.1M from the PPP funds

In other news, it was recently revealed that Nikola Motor received $4.1 million from the coronavirus Paycheck Protection Program funds. The company recently announced a deal to go public by merging with VectoIQ, which valued the truck maker at more than $3 billion. However, the merger has yet to be finalized. Asked by CNBC, Nikola Motor sent a statement saying that the PPP funds will act as a cash bridge fund to retain some 300 employees during the pandemic as the merger closes.

“There’s a difference between a high valuation and having cash,” the company said in the statement. “Nikola is a pre-revenue company with a lot of expenses and burn rate is high. Since PPP funds will be used to retain staff, the lifeline follows the spirit of the Act in that we’re preserving high paying jobs,” it added.