Cryptocurrencies have faced some harsh scrutiny over the past couple of months. From crackdowns in China and Texas to ICO scams and market slumps, digital currencies are becoming increasingly infamous. And now, Microsoft co-founder Bill Gates has voiced a particularly startling criticism of the technology.

In a Reddit AMA (Ask Me Anything) today, the software entrepreneur and world’s richest man was asked about his thoughts on cryptocurrencies. His reply suggested he wasn’t a fan of the anonymity associated with it, stating that it is important for Governments to be able to track money exchanges for the purposes of tax evasion and terrorism funding. In addition, the use of cryptocurrencies to buy drugs has meant that they are a rare technology which is ‘fairly’ directly linked to human deaths.