Signature Systems, Inc., the point-of-sale (POS) vendor for Jimmy Johns, has announced that along with the sandwich chain, the customer card information of more than 100 additional small businesses was compromised.

The company said that in some cases, the malware could have been on some restaurant systems from June 16 to mid-September, according to a press release. Customers' names, card numbers, expiration dates and verification codes might have been affected.

The affected locations include various pizza places, spas and bars around the U.S. In total, 324 businesses, including the affected Jimmy Johns locations, were compromised.

Jimmy Johns confirmed its data breach this past week and said it installed encrypted swipe machines and reviewed its policies and procedures for third party vendors.