Airlines are cracking down on “hidden city” ticketing strategies.

If you’ve ever thought about pulling a fast one on an airline by attempting to book a ticket using “hidden city ticketing” you may want to think again.

Lufthansa, the German national airline, announced it is suing a passenger for allegedly missing a leg of his journey on purpose. Why is that possibly a big deal? Because missing a flight on purpose could end up costing airlines dearly.

As Travel + Leisure previously explained, Hidden city ticketing — otherwise known as point beyond ticketing — is when a traveler books a flight from point A to point B to point C, with point B representing a layover. However, the passenger has no intention to ever travel to point C and instead just stops at point B as their final destination. This way, the person is likely able to save money because they are booking a layover ticket instead of a direct flight.

Lufthansa Airlines
Credit: Getty Images

This practice of skipping the last leg of a flight is so popular there’s even a website dedicated to it: Skiplagged, which promotes cheap fares that use hidden city ticketing.

Though the practice could save a little money, it could be harmful to both the airlines and other passengers as well. As George Hobica, founder of Airfarewatchdog told USA Today, hidden city ticketing could deprive other would-be travelers of seats they could use because you booked it instead. This could, in turn, cause airlines to increase pricing on the same routes in the future.

And now you might also get sued.

Lufthansa, The Independent reported, is currently pursuing payment from the passenger who it believes deliberately missed the last leg of the purchasing journey. According to a court document obtained by CNN the unnamed passenger booked a return flight from Oslo to Seattle with a layover in Frankfurt. On the return flight, the passenger did not catch the Frankfurt to Oslo leg of the journey and instead flew from Frankfurt to Berlin on a separate Lufthansa reservation.

Though an initial ruling found in the passenger’s favor, the airline has been given permission to appeal. It is currently seeking $2,385 in compensation.