After Donald Trump’s call to stop Muslims from entering the U.S., many on social media began comparing him to dictators of the past. But some took it a step further by comparing him to Harry Potter’s nemesis, Lord Voldemort.

Harry Potter author J.K. Rowling didn’t agree with that though. She wrote on Twitter that Trump is far worse.

“How horrible. Voldemort was nowhere near as bad,” the author write, including a link to a BBC News story about the comparisons.

As previously reported, Trump announced on Monday that he wants the U.S. government to stop admitting any Muslims into this country, following the attack in San Bernardino, California. Even before Monday, Trump took a hard-line against Muslims, even suggesting that some should be forced to use special IDs.

While the move has been embraced by his supporters, many have considered this an un-American move. The Philadelphia Daily News compared Trump to Adolf Hitler with the headline “The New Furor.” Even former Vice President Dick Cheney criticized the idea.