Alphabet’s Google told Reuters this week it is developing an alternative to the industry standard method for classifying skin tones, which a growing chorus of technology researchers and dermatologists says is inadequate for assessing whether products are biased against people of colour.

At issue is a six-colour scale known as Fitzpatrick Skin Type (FST), which dermatologists have used since the 1970s. Tech companies now rely on it to categorise people and measure whether products such as facial recognition systems or smartwatch heart-rate sensors perform equally well across skin tones.

Critics say FST, which includes four categories for “white” skin and one apiece for “black” and “brown,” disregards diversity among people of colour. Researchers at the US Department of Homeland Security, during a federal technology standards conference last October, recommended abandoning FST for evaluating facial recognition because it poorly represents colour range in diverse populations.

In response to Reuters’ questions about FST, Google, for the first time and ahead of peers, said that it has been quietly pursuing better measures.