Last week, Marriott revealed that a massive data breach may have affected up to 500 million people who made hotel reservations through Starwood’s online database. It is believed to have been one of the largest customer database breaches in history.

On Monday, Marriott told MarketWatch that the company will pay for a new passport for any customer who believes their identity was compromised by the breach through a process set up by the company.

“As it relates to passports and potential fraud, we are setting up a process to work with our guests who believe that they have experienced fraud as a result of their passports being involved in this incident. If, through that process, we determine that fraud has taken place, then the company will reimburse guests for the costs associated with getting a new passport,” a spokesperson told the website.

Marriott estimates that up to 327 million guests may have had their passport number compromised. If so, this will be a costly fix as a new U.S. passport costs $110.

The data breach could affect anyone who booked a Starwood hotel — including W Hotels, St. Regis and Westin Hotels — anywhere from 2014 to Sept. 10, 2018.

Information compromised in the breach could include name, mailing address, phone number, email address, passport number, Starwood Preferred Guest account information, date of birth, gender, arrival and departure information, reservation date, and communication preferences. Some credit card information may also have been exposed in the breach.

Those worried about the security of their personal information can enroll in a free identity theft monitoring program through Marriott. Customers can also contact a call center (phone numbers are available here) for more information.