Fashion retailer Forever 21 revealed that it has suffered a data breach at some of its stores.

According to news from Fortune, customer payment card information was compromised at certain point of sale devices in stores when the encryption on those devices was not operating. The company, which operates more than 815 stores in 57 countries, did not say which specific locations were affected.

The results were part of an investigation Forever 21 started after it received a third-party report suggesting the unauthorized access. The Los Angeles-based company said the probe was focused on transactions made at its stores between March and October of this year, and that since the investigation was ongoing, it could not give complete findings.

Earlier this year, Forever 21 partnered with mall owner GGP Inc. to introduce a new freestanding brick-and-mortar store dubbed Riley Rose. With the opening of this new store, which already has 13 locations at GGP malls, the retailer will have the opportunity to experiment and focus more on social media-friendly millennials.

“Forever 21 is always ready to expand into new concepts, and has partnered with GGP to open stores in 13 of their top tier locations," said Forever 21’s CEO, Do Won Chang. "These new, experiential spaces will be focused on accessories, cosmetics and home goods for the millennial consumer. We will open 10 stores in 2017 and follow up with three more in 2018.”