If it weren’t for a glitch in Facebook’s fact-checking partnership, one of this week’s biggest viral hoaxes might not have reached as many people.

In Brazil, a false meme posted Jan. 14 that claimed a federal judge ordered prisons to remove power outlets got nearly 200,000 engagements on Facebook. That’s in spite of two debunks published days later by fact-checkers at Aos Fatos and Agência Lupa, which both partner with Facebook to find, debunk and decrease the reach of misinformation on the platform.

Per that partnership, once a fact-checker rates a story, image or video as false, its future reach in the News Feed decreases by up to 80 percent; the fact check appears in a “Related Articles” section below the hoax; and users receive a warning before sharing it. (Disclosure: Being a signatory of the International Fact-Checking Network’s code of principles is a necessary condition for joining the project.)

But a glitch in the system has been letting users share some bogus images with no warning that they were false.

When Poynter originally shared (and then promptly deleted) the Brazilian hoax for testing purposes earlier this week, we received a warning saying that there was additional reporting from Aos Fatos that debunked the meme. That warning came after trying to share the hoax from a Page-level view of the image.