They ran an extra seven kilometres on their half-marathon. And all they're getting is a lousy T-shirt.

Granted, it would be a commemorative T-shirt, offered by the organizers as an apology for inadvertently adding the extra mileage to the race on Sunday.

Organizers came up with the T-shirt apology after runners vented anger on social media at the Standard Chartered Bangkok Half-Marathon, which was mistakenly extended by almost seven kilometres. An error by race officials along the route meant participants ran 27.6 kilometres, rather than the usual 21 kilometres.

Some 6,000 runners raced and everyone — even those who didn't finish — will get a special jersey to wear like a badge of pride, said Songkram Kraison, vice-president of the Jogging Association of Thailand, one of the event's two organizers.

"The T-shirt will say, 'Finisher of 27.6 km,"' Songkram told The Associated Press. "The shirts are meant to apologize and also to honour runners who ran in the longer version of the half-marathon."

The Jogging Association of Thailand's website posted a statement Tuesday saying it will send the shirts by mail within 45 days.

The race looped through Bangkok's historic district, past the Grand Palace, monuments and Buddhist temples, with half-marathon participants sharing the route with full-marathon runners until a specified turn-off. That's where the error occurred, according to organizers, who said officials stationed along the route accidentally directed half-marathon runners to make a U-turn at the wrong spot, which added the extra distance.

"We deeply regret this unfortunate mistake," the Jogging Association of Thailand said in an apology posted in Thai and English on websites and Facebook pages connected with the event. "We admit our mistake and would like to apologize."

The T-shirt is meant to "express our admiration for your spirit in bravely overcoming the obstacles," the letter said.