Tesla has issued a voluntary recall on the Semi, a first since the company began deliveries of the heavy-duty electric trucks to customers in December 2022.

According to recall filings posted on the website of the National Highway Traffic Safety Administration, 35 Semi trucks were affected. The trucks were built with an electronic parking brake valve module found to contain a defect by supplier Bendix in February 2023.

The defect left drivers vulnerable to “rollaway” incidents and increased the likelihood of a crash. According to a recall notice, the defective modules may “fail to move into the park position when the parking brake is activated” leaving drivers unaware their Semi could roll away. The parking brake component defect has not resulted in a crash or any damages, according to the filings.

While Tesla showed off the design of the Semi in late 2017, it only began producing the trucks in Nevada last year and began deliveries to early customer Pepsi at a marketing event late last year.

In filings on the NHTSA site, Tesla said it will “replace the parking brake valve module with a revised part with improved internals that prevent air leakage and allow the driver to engage and disengage parking brakes.”

Elon Musk‘s electric vehicle maker is expected to issue its first-quarter, 2023 vehicle production and deliveries report this weekend. Tesla has not previously broken out Semi production and delivery numbers in its quarterly updates.