AT&T this week acknowledged that DirecTV has been charging the wrong regional sports fees to some customers and is now issuing bill credits to those who paid more because of the mistake.

“We have identified a small percentage of customers who are receiving some inaccurate bills for regional sports network fees,” an AT&T spokesperson told Ars yesterday. “We are working as quickly as possible to notify those customers and issue credits. We apologize for the error.” AT&T bought DirecTV, the nation’s largest satellite TV provider with about 21 million customers, in 2015.

The mistake affects bills going back to late January. Customers will not have to do anything to get the credit, as it will be issued automatically.