Microsoft has released an update for the Surface Pro 3 that’s supposed to fix issues preventing some units from holding a full battery charge.

The problem began popping up over the past few months, with Surface Pro 3 owners reporting that their machines couldn’t stay charged for more than an hour. Microsoft has now identified the problem, saying that certain units have been failing to properly measure their full battery capacity, preventing them from receiving a full charge.

Microsoft equates the issue to a broken fuel gauge in a car. "If the fuel gauge isn’t working right, the car would also not be able to fill the tank — even though the tank is fine," Microsoft writes. Keeping the metaphor going, Microsoft says the actual batteries inside these Surface units are perfectly fine and should begin to function properly after the update is installed.

People who paid for a replacement have to wait to hear about refunds

The changes may not take effect immediately, however. Microsoft says the issue will "self-correct over the next several charge and discharge cycles," so you may have to run the battery down a few times before it recognizes full charge again.

Note that full charge will only be whatever a given Pro 3 unit is still capable of holding — these machines are two years old at this point and likely have diminished battery capacity. That said, they ought to be capable of running off battery for way more than an hour.

Microsoft hasn’t announced yet what it’ll do for people who paid to have their unit’s seemingly faulty battery replaced. The company says it’s looking into which customers were affected — that is, trying to tell who actually had a faulty battery and who simply ran theirs down — and will reach out to people impacted by the bug who paid for a replacement within 30 days.