Harry Potter film villain Tom Felton said he was "heartbroken" after joining the boy wizard's website - and finding himself put in the wrong house for his character.
The actor played Draco Malfoy throughout the on-screen adventures, one of the dastardly characters who belonged to Slytherin house at Hogwarts School.
But after the 27-year-old signed up for the Pottermore site set up by author JK Rowling, he was placed in Gryffindor - home to Harry, Hermione Grainger and Ron Weasley.
Tom, who now stars in US detective series Murder In The First, wrote on Twitter: "Today was the day. I finally did it. I joined Pottermore and was sorted into ... Gryffindor. Heartbroken."
He added the hashtag #slytherinforlife.
JK herself responded by saying she knew he would be placed in Gryffindor, which is characterised by pupils who are courageous and chivalrous.
She wrote back to him: "I could've told you that years ago. I just didn't want to spoil your motivation."