Merriam-Webster defines a mile as a unit of measurement equal to 5,280 feet. But in the increasingly byzantine world of frequent flier mileage reward programs, the term has little or no connection to physical distance. In 2015, United and Delta joined Southwest, Jet Blue and other airlines that award miles based upon ticket price and class, rather than distance traveled. American Airlines followed suit in August 2016.

I wasn’t aware of this reconfiguration when I booked a family trip to Australia and Indonesia on the United Airlines website last summer. I was seduced by the ticket price, $1,206 each, and the 21,393 frequent flier miles I thought we would accrue.

When I got home, I found the proverbial lump of coal in my United Mileage Plus account stocking: a paltry 2,120 miles earned for a six-flight trip that took us from Redmond, Ore., to Sydney, Australia, via San Francisco, with a side trip to and from Denpasar, Indonesia. I called United, assuming that they’d somehow left a zero off my mileage reward. “No, sir, 2,120 miles appears to be the correct reward for the trip,” the polite young woman who double-checked my flight activity said.

She went on to explain the details of United’s relatively new mileage accrual policy. Ordinary Mileage Plus members like me now get five miles for every dollar spent. (Frequent fliers with a higher status can get up to 11 miles per dollar spent.) But I had spent $1,206 on each ticket, so how did I get only 2,120 miles?