Mobile working is the future for many companies, but anathema to Elon Musk. The new Twitter boss announced the return to the previous system in his first email to the workforce, the Bloomberg news agency reported on Thursday. He expects employees to spend at least 40 hours a week in the office. Twitter was initially unavailable for comment.

Musk had previously made similar announcements at his other companies such as the space company SpaceX or Tesla. He told the employees of the electric car manufacturer in an email in the summer: “If you don’t show up, we will assume that you have resigned.”

Musk acquired Twitter for $44 billion two weeks ago. Immediately afterwards, he threw out the previous boss, Parag Agrawal, and other high-ranking managers. He also fired around half of the approximately 7,000 employees previously.