Singer Rita Ora has joined the cast of Fifty Shades of Grey, as Mia, Christian Grey's adopted sister, but most don't appear to be thrilled with the decision. 

"It's official! I've been cast in @FiftyShades of Grey as Christian's sister Mia. #FiftyShades," she tweeted on Monday.

In the book, Mia is described as an outgoing person with a bubbly personality. She's also tall and curvaceous as well as raven-haired with a bob cut.

Some of the Roc Nation singer's fans were content with the casting news and took to Twitter to express their positive opinions. 

"I really didn't want to see the Fifty Shades of Grey movie cus I couldn't get into the book but since @RitaOra is in it, I'm going to see it," tweeted one.

"Heard that Rita Ora will be casting in Fifty Shades of Grey. She will be Christian Grey's sister. Okay now that's a movie not to miss," tweeted another.

However, most weren't as welcoming of Ora's role in the film.

"This is going to be the worst film ever," wrote one along with an article of Ora's casting news.

"You better not mess this up! Nobody wanted you for the part, just saying," tweeted another with the handle @TeamFiftyShades. "Guys, I know it sucks that they picked Rita as Mia, but we shouldn't let her ruin the movie for us."

Shooting for the movie began in Vancouver, Canada on Monday and the film is expected to arrive in theaters in February 2015. Jamie Dornan and Dakota Johnson star as the lead characters, Christian Grey and Anastasia Steele. 

The E. L. James best-selling book turned movie, also stars Max Martini as Christian's bodyguard Jason Taylor and newcomer Eloise Mumford as Anastasia's roommate Kate Kavanaugh.

Tags: Fifty Shades Of Grey Rita Ora