An apparent heart rate monitoring “bug” introduced with the latest Apple Watch update isn’t actually a bug at all, Apple says. The company has simply tweaked the way in which its new wearable measures heart rate, presumably to make it more accurate.

After updating to the Watch OS 1.0.1 software, many Apple Watch owners found that the device was no longer recording their heart rate every ten minutes like it used to. We all assumed this was an issue that needed fixing, but not according to an update on Apple’s website.

“Apple Watch attempts to measure your heart rate every 10 minutes,” the Cupertino company says, “but won’t record it when you’re in motion or your arm is moving.”

If you’re on the go all day, then, you probably won’t get heart rate readings as frequently as someone who is sat still behind a desk most of the time. That wasn’t the case with Watch OS 1.0, which measured heart rate every ten minutes regardless of movement.

It’s unclear why Apple made this change with its latest update. Some speculate it could be to improve battery life, but it was likely to make heart rate readings more accurate; most heart rate sensors ask you to keep still while they take a reading for increasing accuracy.

The change won’t affect readings during a workout, because Watch is programmed to take a reading every 10 seconds regardless of whether you’re arm is moving or not. But of course, that means you need to remember to start a workout in the Workout app.