Amazon is cracking down on warehouse theft — by its own employees.

The e-commerce giant is reimplementing measures it had in facilities before the pandemic, Bloomberg reports, including making workers exit warehouses through metal detectors and asking them to register their personal phones with the company so security doesn’t think they were pilfered.

“We’re always working to make our facilities more safe and secure for our employees and for companies of all sizes that put their trust in us to store their inventory,” Amazon spokesman Steve Kelly told Bloomberg. “As one part of that, we’ve made the decision to restore some practices that we had suspended to support social distancing during the pandemic.”

Workers will soon have to share part of the serial number of their phone with warehouse security and put a sticker on it that confirms its theirs. The company’s decision to register phones signals it isn’t going reimplement a phone ban it had for warehouse workers before the pandemic. Amazon had wanted to reimplement the policy, Bloomberg reports, but faced worked backlash after six employees died when a tornado hit a company facility.

Amazon previously faced a lawsuit that went all the way to the Supreme Court over its employee theft prevention policies. Workers said it could take up to 25 minutes to leave the warehouse because of long security lines and wanted backpay for the time. The high court ultimately sided against the employees, who had been hoping for a $100 million-plus payout.