The Xiaomi Mi Band 2 has been available since June of last year and it’s a great budget fitness tracker that includes automatic heart rate sensors. The only problem with the device seems to be it has trouble reading the heart rate of people who have a dark skin complexion when compared to someone who has a fairer skin complexion.

This problem first cropped up in October last year, just two months after the launch of the device. In a thread entitled, “Mi Band 2 Heart Rate measure not working on Black People” several people are reporting that the device is unable to measure the heart rate of those with dark skin, but can measure it just fine when placed on lighter parts of their body, such as the palms of their hands.

Here are some of the reports from the forum:

I have bought the mi band 2 and seems that the heart rate measure is not working on black people. We have done some tests with the same bracelet on several people. The heart rate measure works well on white people and failed each time on black skin. I bought the mi band 2 since one week and the heart rate measure still not working on me. I tried using another mi band 2, the result is the same i.e. works well on white while it’s not working well me. Are you aware of this technical issue ? It’s embarrassing because I bought for this feature.

To their credit, Xiaomi has marked the issue as being worked on, but that hasn’t stopped the complaints piling up that the device just doesn’t seem to work very well with dark skin. This isn’t the first time we’ve seen something like this, either. When Microsoft’s Kinect first debuted in 2010 it had trouble detecting people with dark skin, too.