A British bookseller announced that it’s donating to a transgender charity for every sale of a book by Harry Potter author J.K. Rowling, LGBTQ Nation reports.

The Second Shelf, a London bookstore that sells rare books by women authors, made the announcement last week on Twitter with a post reading, “Making a donation to @Mermaids_Gender every time we sell J K Rowling.”

Mermaids is a British organization that advocates for the rights of young transgender people.

The Second Shelf’s announcement is almost certainly a reaction to a controversy that Rowling sparked in December, when she tweeted her support for a woman who lost her job at a think tank after she made comments seen as hostile to transgender people.

“Dress however you please,” Rowling tweeted. “Call yourself whatever you like. Sleep with any consenting adult who’ll have you. Live your best life in peace and security. But force women out of their jobs for stating that sex is real?”

Her comments led to widespread condemnation from the trans community and their supporters, who accused her of being a “TERF,” or “trans-exclusionary radical feminist,” a term used to describe cisgender feminists who don’t support trans rights.

Her tweet clearly didn’t sit well with the Second Shelf. The shop’s Twitter biography reads in part, “Trans women are women!”

Rowling’s latest book, Troubled Blood, written under the pen name Robert Galbraith, will be published in September, according to a news release from Little, Brown, on Wednesday.

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