Harry Potter creator J.K. Rowling is facing a tidal wave of criticism after tweeting her support for a woman who lost her job over her opinion that “men cannot change into women.”

In March, a think tank declined to renew the contract of Maya Forstater, who had tweeted that she thought biological sex was immutable, a view widely seen as hostile to transgender people. She challenged her dismissal at an employment tribunal, but a judge said her opinions did “not have the protected characteristic of philosophical belief,” the Guardian reports.

On Thursday morning, Rowling took to Twitter to share her opinion that Forstater had been treated unfairly:

Rowling’s tweet was met with derision from readers accusing her of being a “TERF,” or a “trans-exclusionary radical feminist”⁠—a term used by supporters of trans rights to refer to feminists who are dismissive of, or hostile to, issues facing transgender people.

“As a gay man that found safety in Hogwarts throughout my childhood—knowing that Trans people wouldn’t be able to have that safety breaks my heart,” wrote Shahmir Sanni in a response to Rowling.

“As a cis queer woman with a trans sibling, it’s not enough to support the LGB community at the expense of the trans community,” Ashly Perez replied.

And Casey McQuiston, author of Red, White Royal Blue, broke her Twitter hiatus to tweet, “fuck what your childhood heroes say. trans people are real. trans people deserve to be protected, recognized, supported, and loved. if that infringes on your idea of feminism, you’re not actually a feminist at all. you’re a bigot.”

Michael Schaub is an Austin, Texas–based journalist and regular contributor to NPR.