Antifa protesters in Boston accidentally turned on one another over the weekend, when one protester attacked a man simply because he looked like he could be a Nazi.

News website Splinter posted a video of the aftermath of the attack on its Twitter account Tuesday.

"He is on our side!" This anti-white nationalist protester was punched in the face after being mistaken for a neo-Nazi in Boston: pic.twitter.com/Hi3U02vjBc — Splinter (@splinter_news) August 22, 2017

In the video, a white man with a shaved head nurses a bad cut.

"You do not hit somebody that you assume is a Neo-Nazi," an organizer lectures. "You cannot do that!"

The man appears to get woozy, and has to sit down and rest. His fellow protesters offer to get water and a medic.

Splinter asks the man if he plans to stay and remain at the protest.

"I'm not exactly sure right now," he responds dryly.

The Boston protester was hardly the first to be mistakenly identified as a member of the alt-right. An innocent Arkansas engineer was falsely accused of being a Nazi following the Charlottesville, Va. rally earlier this month and became a target of doxxing and online harassment.

Earlier in the year, a University of California, Berkeley student wrote in the New York Times that they witnessed a left-wing protester attacking a man in a suit, assuming he was a supporter of alt-right provocateur Milo Yiannopoulos. In reality, the victim was a Syrian Muslim.