People looking to walk into an Apple retailer and buy an iPhone with cash will be out of luck. The company is now accepting only credit or debit card payments for the devices so that it can track who purchases the phone, according to an employee at the Apple Store in New York’s SoHo neighborhood.

The new policy is Apple’s attempt to prevent people from purchasing and then unlocking and reselling iPhones, a situation that has been a problem for the company. Apple won’t let anyone without a credit card or debit card in their name purchase iPhones, according to an unidentified Apple Store employee in a phone interview.