Dern first confessed to the hilarious habit in an interview with Stephen Colbert before the film's release last year.
"I was back in my bedroom at eight years old," she said of her Star Wars experience.
"Doing the scene, I went, 'Pew-pew!' They've taken the sound out, I don't think you'll hear that in the movie. I was so excited! I mean, it's Star Wars!"
Dern's "pew" moment will join a long line of Star Wars gaffes and bloopers savoured by eagle-eyed fans of the franchise — starting all the way back in the original 1977 film with the unfortunate Stormtrooper who banged his head on the Death Star.
She's also not the first Star Wars actor to fall victim to the "pew" temptation: Hayden Christensen revealed that he was scolded by Star Wars creator George Lucas for the very same thing during his time playing Anakin Skywalker.
"'Hayden, that looks really great,'" Christensen recalled the director saying, "'but I can see your mouth moving. You don't have to do that. We add the sound effects in afterwards.' I was just so focused I wasn't even aware I was doing it."
