McDonald's is betting it can speed up its drive-thru service -- and real food is on the line.

The burger chain is promising that guests at designated restaurants will receive their food in under 60 seconds after paying for it at the drive-thru, reports the Miami Herald. To ensure there is no cheating, customers will be handed timers when they pay for their orders. If it takes more than 60 seconds for the McDonald's crew to assemble and deliver the meal, the chain promises to pay for a complimentary lunch item on a future visit.

Sadly for McDonald's lovers who lunch across the U.S., the promotion is only running at participating South Florida restaurants. The time window is also small: weekdays from noon to 1 p.m. through Aug. 29.

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Even though the test is limited, the intense time limit could help McDonald's untangle its struggles keeping up with fast food. The influx in new and complicated menu items in recent years has slowed down the fast food giant. In 2013, the average service time was 189.5 seconds, McDonald's slowest average speed in the last 15 years. Last year, the chain announced plans to add a third drive-thru window at new and remodeled restaurants to speed up service.

Aside from time, McDonald's is fighting to stay on top – or even near the top – in the fast-food industry on multiple fronts. Global same-store sales are flat, and U.S. same-store sales have been falling in recent quarters. Last month, McDonald's meat supplier in China was revealed to be selling expired meat, leaving McDonald's menus in the area meatless for weeks. And, McDonald's was dealt a harsh blow last week when the National Labor Relations Board deemed McDonald's a joint employer in employees' lawsuits against the chain.  

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