By Ariana Bacle
Updated July 11, 2015 at 07:25 PM EDT
Credit: Clive Brunskill/Getty Images)

Serena Williams won Wimbledown Saturday, so J.K. Rowling went on Twitter to express her excitement: “I love her,” she wrote. “What an athlete, what a role model, what a woman!” One Twitter user responded by writing, “ironic then that main reason for her success is that she is built like a man” — so Rowling took that opportunity to slam said Twitter user.

“‘She is built like a man,'” Rowling replied along with a photo of Williams wearing a form-fitting red dress. “Yeah, my husband looks just like this in a dress. You’re an idiot.” See the exchange below.