It’s frustrating! Your ever-ready carry-on — the one you know fits wheels-first into the overhead bin on every aircraft you’ve flown — is suddenly “too big.” Given the opportunity, you can probably prove it fits. Or perhaps a retrofit has ever so slightly changed the dimensions of the overhead bin on the aircraft you’re boarding. Maybe you’re so fed up with diminishing returns from airline loyalty programs, you decide try a different carrier only to discover the bins are smaller.

The International Air Transport Association this week announced an initiative aimed at minimizing carry-on confusion by standardizing acceptable carry-on bag size across the board. IATA member airlines and aircraft manufacturers agreed upon an optimum size guideline for carry-on bags: 21.5 x 13.5 x 7.5 inches. In theory, that means all passengers should be able to store one carry-on bags on board aircraft with 120 seats or more.

There’s even an “IATA Cabin OK” logo to signify to airline staff that a bag meets the agreed-upon size guidelines. A number of major international airlines have expressed interest and will soon be introducing the guidelines into their operations. Several major baggage manufacturers have developed products in line with the optimum size guidelines. Bags carrying the identifying label will be in retail shops later this year.