Facebook is blocking fake news sites from using its advertising network to generate revenue, the Wall Street Journal reported Monday, following a similar move by Google.

The restriction follows speculation that fake news on both of the companies’ sites may have influenced the voters deciding on this year’s election.

It means that fake news sites now join misleading, illegal and deceptive sites as barred properties by the Facebook Audience Network.

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“While implied, we have updated the policy to explicitly clarify that this applies to fake news,” a Facebook spokesperson said in a statement to the WSJ. “We vigorously enforce our policies and take swift action against sites and apps that are found to be in violation. Our team will continue to closely vet all prospective publishers and monitor existing ones to ensure compliance.”

Facebook has been accused by some critics of contributing to Hillary Clinton’s loss to Donald Trump last week by allowing the publication of fake news.

Also Read: John Oliver Slams Facebook News Feed's 'Cesspool of Nonsense' During Election (Video)

“Everyone has the right to say what they want, have access to sites that they want, share what they want,” Clinton campaign chief digital strategist Teddy Goff told Politico. “But a publisher with a record of making stuff up is not likely to rank that highly on Google, and the equivalent ought to be the case on Facebook.”

On Sunday night, HBO’s “Last Week Tonight” host John Oliver slammed the social media hub as a “cesspool of nonsense” and pointed to a fake story about the Pope endorsing Trump that was shared almost 1 million times.

“Fake facts circulate on social media to a frightening extent,” Oliver said. “There is now a whole cottage industry specializing in hyper-partisan, sometimes wildly distorted click bait.”

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Google has also been strongly criticized for giving too much prominence to false news stories.