At the age of 9, Watson had a hilarious habit that would ruin takes.

By Nick Romano
March 07, 2017 at 07:47 AM EST

Here’s more definitive proof that young Emma Watson was in tune with her Harry Potter character, Hermione: the actress, at age 9, was caught inadvertently mouthing her costars’ lines in in Sorcerer’s Stone.

Jimmy Kimmel showed Watson what he called an “outtake” from the Potter film on Monday night’s Jimmy Kimmel Live, in which Watson was spotted mouthing Rupert Grint’s lines during a take. (“You’re helping them with their lines,” Kimmel joked.)

“You laugh, this is actually quite traumatic for me because I created issues because of this,” she said. “Yes, I would ruin takes. [Director] Chris [Columbus] would be like, “Cut. Emma, you’re doing it again. You’re mouthing Dan’s lines,’ and I’d be like, ‘Ooo, I’m so sorry, so sorry. Oh, I feel so bad.’ But I couldn’t help myself.”

She joked, “I was such a loser, I really loved those books, I really wanted to do my job well, and I kind of overdid it.”

Columbus revealed more behind-the-scenes stories on Harry Potter and the Sorcerer’s Stone on EW’s Binge podcast. “The thing we shot on the first day of Sorcerer’s Stone was the final train sequence where Harry looks at Hogwarts and Emma, Dan, and Rupert are huddled outside of the train,” he recalled. “It was a big thing in the books about [Hermione’s] teeth. She sort of had an overbite, so [Emma’s] wearing fake teeth in that scene.”

Now it’s time to re-watch the first film and see if you can spot these moments.

Watch Watson in the clip above.