Whole Foods, the grocery chain recently acquired by Amazon for $1.7 billion in late August, revealed on Thursday that a point-of-sale data breach had compromised customers’ credit and debit card details.

The company said it recently received information regarding unauthorized access of payment card information used at certain venues such as taprooms and full table-service restaurants located within some stores.

The affected venues use a different point of sale system than the company’s primary store checkout systems, and payment cards used at the primary store checkout systems were not affected, according to Whole Foods.

The company also revealed that it has launched an investigation into the hack, but urged customers to closely monitor their payment card statements.

Amazon.com systems were not affected by the breach, the company was quick to point out.