A group of laid-off Twitter employees must drop their class-action lawsuit against the company, which accuses the social media giant of skipping out on its promised severance pay, according to a ruling from a federal judge on Friday.

U.S. District Judge James Donato told the employees that they had to instead make their claim in private arbitration, citing their employment contract with the company.

The ruling said the contract provided the employees an opportunity to opt out of non-mandatory arbitration, but they did not. The contract also included a class action lawsuit waiver, mandating that employees bring any disputes on an individual basis to arbitration.

The move from the employees to sue the company came after Elon Musk acquired Twitter and handed down job cuts soon after. The group of laid off Twitter employees filed the lawsuit in November, saying the company did not provide enough notice before letting them go.

The employees pointed to the federal Worker Adjustment and Retraining Notification (WARN) Act, which mandates that employers give 60 days of notice for company-wide layoffs. The employees argued Musk was in violation of the law.

Musk said after the work cuts that the company was offering employees three months of severance, but some employees have argued Twitter has not kept that promise.

Twitter laid off around 3,700 employees in November.

The lawyer representing the Twitter employees pushed back on the idea that the judge’s ruling was a win for Twitter and Musk. Shannon Liss-Riordan said in a tweet that they were expecting the ruling from the court and that they have filed 500 individual arbitration claims.

“This is not a win for @elonmusk,” Liss-Riordan said in the post. “Twitter still has to answer claims in court, on top of the arbitration battles.”