Anyone who has had to repeatedly charge their phone throughout the day knows that battery life is a key measure of a smartphone’s quality. The iPhone 5 has a decent battery life — except, perhaps, if you happen to have bought yours at the wrong time.

Some iPhone 5 devices sold between September 2012 and January 2013 have a battery problem leading to a shorter battery life, Apple said Friday. Users experiencing battery issues may have bought one in a series of iPhone 5 devices that were affected by charging problems.

“Apple has determined that a very small percentage of iPhone 5 devices may suddenly experience shorter battery life or need to be charged more frequently,” Apple said in a note.

Owners of the iPhone 5 who are having issues can input their phone’s serial number on Apple’s page and see if they qualify for a free battery replacement. The replacement is available in the U.S. and China as of Aug. 22, and in other countries as of Aug. 29.

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