Elon Musk has warned Twitter’s employees to prepare for 80-hour work weeks, the end of subsidised meals and strict prohibitions on working from home.

While Musk has fired nearly 3,700 Twitter employees globally, in his first address to the remaining Twitter’s employees after buying the social media platform for $44 billion, he said the company can go bankrupt if it does not start generating more cash, Bloomberg reported, citing people aware of the matter.

Musk warned employees of “tough times ahead” in an email sent late on Wednesday, adding that there was “no way to sugarcoat the news” regarding the company’s economic future.

“If you don’t want to come, resignation accepted,” he said, according to a person familiar with the matter.

When he was asked about the prospect of attrition, Musk said, “We all need to be more hardcore.”

In discussing Twitter’s finances and future, Musk said the company needed to move with urgency to make its $8 subscription product, Twitter Blue, something users will want to pay for, given a pullback by advertisers who are concerned about harmful content.

Musk’s takeover has shielded Twitter from the scrutiny of the stock market but it has also burdened the company with over $13 billion in debt. 

The resignation of Twitter’s top information security officer, privacy officer, and chief compliance officer earlier on Thursday raised questions about the company’s capacity to maintain the security of its platform. 

Some advertisers have pulled back from the social network because they are worried about Musk’s intentions for content policing.

Currently, Twitter is subject to a consent decree with the Federal Trade Commission that controls how the firm uses user data and carries the risk of penalties for violations.