Birds of Prey opened to $33 million in the United States, below its projected opening of $50-55 million

Margot Robbie‘s Birds of Prey is reportedly flying off with a new name.

According to Entertainment Weekly, the comic book film’s official title — Birds of Prey (and the Fantabulous Emancipation of One Harley Quinn) — has been changed in some movie theaters to place the iconic main character front and center. The outlet reports that theaters are now listing the movie as Harley Quinn: Birds of Prey.

Theater websites including Regal, Cinemark and AMC all reflect the change.

Warner Bros., which distributed the film, did not immediately respond to PEOPLE’s request for comment.

It remains unclear what prompted the reported change, but it comes after Birds of Prey, which is in the DC extended universe, had a disappointing opening weekend at the box office. According to Box Office Mojo, the film opened to $33 million in the United States — below its projected opening of $50-55 million, EW reports. However, the flick performed better internationally, making $79.5 million worldwide over the weekend.

Margot Robbie in Birds of Prey
| Credit: Claudette Barius/ © DC Comics

Birds of Prey is the first standalone movie for Robbie’s character of Harley Quinn, who was also seen in 2016’s Suicide Squad. Despite the low box office opening, the film got positive early reviews from critics, who called it “fun” and “breathing new life into a stagnant genre.”

The movie follows Robbie as Harley Quinn as she begins a new life without the Joker, only to find herself with a target on her back. Unprotected and on the run, Quinn teams up with a group of deadly women as she faces the narcissistic crime boss Black Mask.

Birds of Prey also stars Rosie Perez, Mary Elizabeth Winstead and newcomer Ella Jay Basco.

(L-r) ROSIE PEREZ as Renee Montoya, MARY ELIZABETH WINSTEAD as Huntress, MARGOT ROBBIE as Harley Quinn, ELLA JAY BASCO as Cassandra Cain and JURNEE SMOLLETT-BELL as Black Canary in Warner Bros. Pictures’ “BIRDS OF PREY (AND THE FANTABULOUS EMANCIPATION OF ONE HARLEY QUINN),” a Warner Bros. Pictures release.
Birds of Prey
| Credit: Claudette Barius
Margot Robbie
Margot Robbie at the premiere of Birds of Prey
| Credit: Jeff Spicer/Getty

Robbie, 29, who also worked on the film as an executive producer, recently told Nerdist she was motivated to make Birds of Prey to bring more female characters to the spotlight.

“During Suicide Squad, when we would go to Comic-Con and such, I started to realize there was just such a huge fan base for Harley,” Robbie said. “Whilst I was researching the character I started to read Birds of Prey and first I fell in love with Huntress, and I started looking into all of that. I was like, ‘Wow, there’s so many cool female DC characters and no one knows anything about any of them!’ So what if we had a platform for fans to get to know and fall in love with some of these other amazing women?”

Birds of Prey is in theaters now.