Charlize Theron‘s son, Jackson, isn’t too happy with his mom’s latest costar, Emily Blunt.

While visiting the set of the ladies’ upcoming film, The Huntsman: Winter’s War, the four-year-old tot spotted Emily in her Freya, the Ice Queen costume — and innocently mistook her for another Disney princess!

“I knew the moment I decided to have white hair that that would be the comparison,” Emily, 33, said of her character’s look during a Jimmy Kimmel Live! appearance on Monday, April 18. “Charlize’s son was on set a lot and he was obsessed with Frozen. He really thought I was [Princess Elsa].”

emily blunt the huntsman

Emily in The Huntsman: Winter’s War.

Despite Jackson’s mistake, the pregnant actress admitted she didn’t have the guts to tell the little boy the truth. “He got really disappointed because he saw me in my sweatpants one day with the white hair on,” Emily revealed to host Jimmy Kimmel. “He just looked at me and he goes, ‘Put on your dress.’ He was really bummed about it. ‘Put it on now.'”

RELATED: Emily Blunt Talks Baby No. 2 — See the Adorable Thing She Said!

Charlize, 40 — who previously adopted Jackson in March 2012 and is also a mom to daughter August — stars as Ravenna, the Evil Queen in the highly-anticipated movie, which hits theaters this Friday, April 22!