A few weeks ago, Apple announced a replacement service for those users affected by iPhone 6S units with faulty batteries, which caused them to shut down, even during use. Since the announcement, more users have experienced difficulties, leading many to believe that Apple’s original estimate that only “a very small number of iPhone 6S units” were affected may be untrue.

Users who feel that their iPhone 6S battery life isn’t up to par, or who have experienced the random shut downs, can enter their serial number on Apple’s website and find out within seconds if their iPhone’s battery is eligible for replacement. Even if your iPhone hasn’t experienced the symptoms, it probably wouldn’t be a bad idea to enter your serial to see if you may be affected by the problem in the future.

iPhones affected in this program can be taken to an Apple retail store (schedule a Genius Bar appointment first!) or another Apple authorized service provider to have their battery replaced. Before performing any service, Apple will examine all devices to be sure that they are eligible for the recall, and are in otherwise working order, so this probably isn’t your opportunity to pull a fast one on them.

For those who may be unsure of how to find their serial number, the process is incredibly simple. Apple explains that users should, “Go to Settings > General > About and look for your device’s serial number, IMEI/MEID, and ICCID. If you’d like to paste this information into Apple registration or support forms, tap and hold on the number and copy it.”

Click here to learn more about the iPhone 6S battery replacement program and see if your phone happens to be affected. If so, while not completely necessary since it’s not a safety issue, having your phone’s battery replaced should be added to your to do list.