In a Medium post published today, Tesla employee Jose Moran detailed working conditions at the company’s Fremont factory and called for the factory workers to unionize with United Auto Workers (UAW).

Tesla currently employs more than 5,000 non-union workers at its Fremont, California-based factory. Moran wrote that the workers are often faced with “excessive mandatory overtime” and earn between $17 and $21 hourly, compared with the national average of $25.58 hourly for most autoworkers in the US. The Tesla employee noted that the astronomical cost of living in the Bay Area makes $21 an hour difficult to live on.

The post was Moran’s first on Medium, and Ars could not find a way to contact him for further details.

Moran also claimed that the factory’s “machinery is often not ergonomically compatible with our bodies,” and requires “too much twisting and turning and extra physical movement to do jobs that could be simplified if workers’ input were welcomed.” He added that at one point, six out of eight people on his team were out on medical leave “due to various work-related injuries.”

A Tesla spokesperson told Ars that Moran’s Medium post “is not the first time we have been the target of a professional union organizing effort such as this.”

“The safety and job satisfaction of our employees here at Tesla has always been extremely important to us,” the spokesperson continued. “We have a long history of engaging directly with our employees on the issues that matter to them, and we will continue to do so because it’s the right thing to do.”

Speaking to Gizmodo through Twitter Direct Messages, Elon Musk said, “Our understanding is that this guy was paid by the UAW to join Tesla and agitate for a union,” adding, “Frankly, I find this attack to be morally outrageous. Tesla is the last car company left in California, because costs are so high.” Musk then blamed the UAW for killing New United Motor Manufacturing, Inc (NUMMI), which sold the Fremont factory to Musk in 2010.

Regarding mandatory overtime, Musk said it was occasionally employed “if we are trying to make up for a production stoppage, but it is dropping almost every week,” and he claimed that entry-level wages are better at Tesla than those at UAW factories.

Ars reached out to UAW for comment, but did not receive an answer.

In his Medium post, Moran also noted that “recently, every worker was required to sign a confidentiality policy that threatens consequences if we exercise our right to speak out about wages and working conditions.” The Mercury News said that Tesla lawyer Todd Maron wrote a letter in January stating that “the company respected their workers’ rights to speak freely, but wanted to curb unauthorized disclosures about product launches and vehicle features.”

Update: This story went up with two headlines. One of them, "Tesla employee calls for unionization, Musk says that’s 'morally outrageous,'" could have been construed as Musk claiming that unionization itself is morally outrageous, which was not the case. We have replaced that headline with the other.