Mileage junkies have been hoarding a secret for years that could save passengers up to 30 percent on long-distance flights: buying two tickets instead of one.

It may not make sense, but in the crazy airline world, pairing two discounted tickets and forming your own itinerary can save up to hundreds of dollars on flights to Europe, Asia and Hawaii.

But cheaper doesn’t necessarily mean easier. In fact, it almost never does.

The tradeoffs include rechecking bags (don’t forget those baggage fees), staying overnight in a connecting city, and being marked a “no show” when missing a connecting flight—all of which eliminate the money-saving perk while making the trip all that more difficult.

However, if done correctly, forming your own itinerary could be well worth the effort, and the best part: it’s not against the rules! Read the Wall Street Journal article to find out how to save up to 30 percent on long-distance flights.