Ellen Pao has long been an outspoken and influential advocate for diversity in the world of tech. On Wednesday, the former Reddit CEO called out tech companies directly for something her own former employer is guilty of once accommodating: incel culture.

“CEOs of big tech companies: You almost certainly have incels as employees. What are you going to do about it?” she wrote on Twitter. At the time of this writing, the tweet had been retweeted over 700 times.

Incel is shorthand for “involuntary celibates.” It’s a self-labeled group of men who believe that they have been denied sex and relationships due to a perceived unfair social structure that preferences what they call popular “alpha” males. Incels mostly blame women for denying them what they believe is their inherent right to sex and affection, and their online dens of communication consistently spout misogynistic language and have praised the violent acts of mass killers like Elliot Rodger and Alek Minassian.

Reddit once hosted a large forum for incels, called r/incels. The subreddit was banned in late 2017 for promoting violence and hate speech. Since then, a more vanilla version has appeared, called r/braincels.

During Pao’s tenure at Reddit, she was tasked with clamping down on the site’s problems with hate speech and revenge porn. After Reddit banned several subreddits, Pao became a target for trolls and was subjected to intense harassment and threats. After leaving the company, she co-founded a non-profit called Project Include which works to promote diversity and pay equity in startups.

Pao’s direct challenge to tech companies is an interesting proposal. As incel culture is increasingly recognized as a community that praises — and in certain instances, potentially inspires — real world acts of violence, how will we work to negate their influence? Silicon Valley already has a reputation for inspiring toxic masculinity. Although it sounds extreme, discovering ways to rid tech companies of self-described incels — who certainly do engage in hate speech — could be a step in the right direction.