Jessica Alba has bid goodbye to her brunette locks, or at least for a day or two, as on Nov. 24 the star Instagrammed a selfie of her lying in bed sporting bright blonde hair before posting another pic the next day of herself curiously back to brown ombré, People magazine reports.

Alba's new blonde hair is a change for her role in the upcoming film "Barely Lethal" as assassin Vanessa Knox. One week ago, the actress posted a behind-the-scenes photo to Instagram of her and Hailee Steinfeld performing some very tricky stunts in front of a green screen, captioned, "#girlsrule in @barelylethalmovie @haileesteinfeld #actionhero." 

In the new film directed by Kyle Newman, Steinfeld will play a 16-year-old fellow assassin who just wants a normal life and decides to enroll in a public high school, soon to learn that "being popular can be more painful than getting water-boarded." Samuel L. Jackson, Sophie Turner ("Game of Thrones") and Jaime King also star in the new action-comedy, set for a 2014 release. 

Alba seems to have been going back and forth from blonde to brown during filming over the course of the last few weeks while filming, so the blonde doesn't appear to be anything permanent, especially as the 32-year-old has kept her eyebrows their natural dark shade.

On Nov. 26, Alba stepped out in Santa Monica sporting her natural caramel-colored hair, heading to her office in a black studded t-shirt, leather jacket, loose-fitting printed pants and a massive red Birkin bag.