Days after Media Matters launched a petition urging him to take action, Facebook CEO Mark Zuckerberg committed to working on the problem on fake news at Facebook, writing in a Facebook post that “I want you to know that we have always taken this seriously, we understand how important the issue is for our community and we are committed to getting this right.”

There is mounting evidence about the scope of the crisis of fake news on Facebook. Teenagers in Macedonia ran content farms creating fake news that generated over hundreds of thousands of shares on Facebook during the presidential election. Fake news stories repeatedly trended and were shared across Facebook. A BuzzFeed analysis even found that fake news outperformed real news during the final three months of the election.

Facebook has been slow to address the problem. They only removed fake news websites from their advertising network once Google did the same. Multiple former Facebook employees spoke out and confirmed that Facebook really did have the ability to address the problem but was choosing not to, with Zuckerberg calling the argument that fake news on Facebook influenced the election outcome “crazy.”

But in a November 19th post, Zuckerberg agreed that this is a problem and that Facebook was working on ways to mitigate fake news. His full post is worth reading: