Twitter CEO Elon Musk reportedly sent a notice to staff early Wednesday morning to remind them that working from home is not acceptable.

According to Platformer managing editor Zoë Schiffer, Musk emailed employees at 2:30 in the morning, writing that “office is not optional.” In the email, he complained that half of the San Francisco headquarters was empty the day before.

Musk is not a fan of remote work. Back in November, he ended Twitter’s work-from-home accommodations, telling employees within driving distance of the office that they needed to show up in person or consider their “resignation accepted.”