A musician’s instrument is a precious thing, in both senses of the word: they can be both riotously expensive, and also deeply loved. Airlines, however, have a bad track record of treating instruments less well than they deserve, by losing or wrecking them. The obvious solution — keep it with you, on board, in the passenger cabin — hasn’t always met with a positive response from the airlines, but now it’s official: you are, indeed, allowed to keep your instrument with you so that the airline can’t break it.

Right at the end of the year, when we were all paying attention to other things, the U.S. Department of Transportation issued a final rule that for really-reals implements the policy about musical instruments and aviation.

Under the rule, airlines are required to let passengers bring their musical instruments on-board as their carry-on item. That’s great news for instrumentalists who don’t want to see their guitars crushed in a service elevator, but there are still two big caveats.

One is that airlines don’t have to prioritize musical instruments ahead of any other carry-on luggage. If the bins are full, they’re full and you’re stuck in gate-check land. The DoT recommends that musicians may want to pay the fee for their airline’s priority boarding service in order to snag that precious overhead compartment space before the guy with the 16-ton rolling suitcase snags it all.

The other catch is that as carry-on luggage, instruments need to fit all of the airline’s guidelines for carry-ons. If your guitar case is bigger than the overhead bins, tough luck. So make sure to check the measurements — theirs and yours — before you go. If the instrument is too big to fit in the overhead bin, travelers are permitted to purchase a second seat in which to stow it (but that doesn’t mean they can collect frequent flier miles for it).

And of course, the regulation only applies to the actual airplane part of air travel; the DoT can’t do much about security or customs wrecking your stuff.

The new DoT rule is the latest step in a lengthy process to try to save instruments from indignity and destruction. Congress and the FAA explicitly made it law back in 2012 that musicians are allowed to bring their instruments on board as carry-on items, but that didn’t stop airlines from wrecking a vintage guitar in 2013 or refusing to let two violinists carry their instruments on board in 2014.

To go with the new rule, the DoT has created an online guide for traveling musicians. The guide has links to a PDF of the full rule, a tip sheet for travelers, and complaint forms for officially reporting airlines that screw it up.

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