More than 64,000 of 2014’s Tomorrowland festival-goers have had their data and personal information stolen in a recent hacking.

Tomorrowland is an electronic dance music festival held in Boom, Belgium. Tomorrowland was first held in 2005 and has since become one of the world’s largest and most notable music festivals.

According to De Standaard, the old online server used for Tomorrowland ticket sales had been experiencing suspicious activity.

The affected systems were reportedly shut down, though hackers gained access to the names, addresses, emails, ages, postcodes and genders of 64,000 of that year’s 360,000 attendees. 

“The managers of the Paylogic ticketing system noticed some unusual activity on an older system,” spokesperson Debby Wilmsen told De Standaard. “After careful analysis it appeared that an old database from Tomorrowland 2014 was concerned. The server in question was immediately taken offline.”

“We ask to be vigilant when receiving e-mails about ticket sales, promotions or other addressees that do not come from official Paylogic or Tomorrowland communication channels,” Wilmsen added. “All communication from Tomorrowland is led by tomorrowland.com. Links to Tomorrowland ticket sales can only be found via my.tomorrowland.com or official travel partners.”

Those affected by the hack have reportedly been contacted by Tomorrowland.

Image: Julian Dael