Facebook has denied that its fake news problem had any effect on the presidential election, but a new Chrome extension is trying to help readers easily spot those "questionable sources."

Released on Tuesday, the "B.S. Detector" will flag potentially fake news websites for Facebook users. The extension generates a warning message over the article when users scroll through a feed.

"I built this in about an hour yesterday after reading Zuck's B.S. about not being able to flag fake news sites," said extension creator Daniel Sieradski in a post on Product Hunt. "Of course you can. It just takes having a spine to call out nonsense."

He also pointed out that, although his new project works "well enough," it's currently just a proof of concept. One of the limitations is that it will flag only those sites that Sieradski has included on the list of questionable sources. But users are able to submit requests for additional domains to be included through GitHub. Sieradski also addressed censorship worries by emphasizing that a warning message does not qualify as censorship, adding that the plug-in is voluntary.

Earlier this week, Facebook announced that it would block fake news site from using its ad platform, but has yet to roll out a similar tool to flag sites on user feeds.