Richard Valtr built one of the most valuable hospitality technology companies in the world simply because he was a teen who wanted to stop working the night shift.

“I always remember being 14 years old on my summer holidays, thinking that this was so unfair,” the Mews founder told Fortune at his company’s Unfold conference in Amsterdam on Wednesday. “My hatred went for the systems.”

While his friends were enjoying their summers, a teenage Valtr was working the graveyard shift at his family’s boutique hotel in Prague, hunched over credit card slips at 1 a.m., matching every payment to every guest bill as part of the industry’s dreaded “night audit.” The ritual took roughly two hours, and it had to be done every single night.

That dreaded nightly task became the impetus for Valtr to build Mews, a hotel and hospitality management software that’s used by over 15,000 properties worldwide. Valtr said he created Mews, which acts as a catch-all system for hoteliers to handle bookings, check-ins, payments, and operations, simply because he believed there had to be a better way that manually checking slips. “I kind of channeled all my energy towards the actual tasks,” he says, “because I was like, this is so stupid.”