President Obama used appearances in Germany to chime in on the controversy around fake news on Facebook and other social media platforms, linking the phenomenon to low voter turnout.

“In the United States, if 43 percent of eligible voters do not vote, then democracy is weakened,” Obama said during a joint appearance with German Chancellor Angela Merkel in Berlin, according to a New York Times report.

He then went on to link the low turnout to fake news: “If we are not serious about facts and what’s true and what’s not, and particularly in an age of social media when so many people are getting their information in sound bites and off their phones, if we can’t discriminate between serious arguments and propaganda, then we have problems.”

Facebook in particular has been under fire since the election for helping to spread fake news. Facebook CEO Mark Zuckerberg has pushed back against the idea that his company’s service could have influenced the election, claiming that more than 99 percent of all Facebook shares are “authentic.”

However, a recent BuzzFeed investigation found that the 20 most-shared fabricated stories ahead of the election got more eyeballs than the 20 most-shared genuine stories from mainstream media organizations.

Despite denying responsibility, Facebook has started to take some steps against fake news. The company announced earlier this week that it would block fake news site from participating in its ad network, a step that mirrors a similar announcement this week from Google.

Separately, Twitter has started to take steps against hate and harassment on its platform: The company rolled out filters against abusive language this week, and also proceeded to boot a number of high-profile right-wing extremists off of its service. Twitter users had long demanded that the company move more aggressively to curb abusive behavior.