Twitter has started to remove fake campaign ads that are meant to discourage supporters of Hillary Clinton from voting by removing individual tweets, and in at least one case banning an entire account. This comes after the company initially told a user that those fake ads were not violating its terms of service.

The fake ads in question, which were posted by a self-proclaimed white supremacist on Twitter, encouraged supporters of Hillary Clinton to “avoid the line” and cast their votes via text messaging instead. The ads were using visual language similar to official Clinton campaign material, and one specifically targeted Latino voters with Spanish messaging. Needless to say, there is no option to vote by text messaging in any state.

The fake ads were first spotted by Robert McNees, a theoretical physicist from Chicago, who alerted Twitter’s support staff — only to be told that the messages in question didn’t violate Twitter’s terms of service.

McNees took to Twitter to alert the public of the issue. Buzzfeed reported, and Twitter CEO Jack Dorsey personally responded, saying that he was “not sure how this slipped past us.” Twitter has since removed the ads themselves, and banned the user who posted them in the first place.

Twitter has frequently struggled with content moderation issues, with many users alleging that the service doesn’t do enough to combat abuse. Earlier this year, “Ghostbusters” star Leslie Jones briefly abandoned the service after being the target of a racist hate campaign.

Dorsey personally intervened in that case as well, and the company banned right-wing troublemaker Milo Yiannopoulos from the service as a result. At the time, Dorsey acknowledged that Twitter hadn’t done enough to curb abuse, saying: “We need to do better.”