Lena Dunham says she had the blessing of Catherine Called Birdy author to change the book's ending

Fans of Karen Cushman's 1994 novel Catherine Called Birdy will notice some key differences in the forthcoming movie version.

Speaking at her film's premiere at the Toronto International Film Festival, director and adapting writer Lena Dunham said that she made the call to have the film end on a lighter note than its source material, but she didn't do it without Cushman's approval.

"I felt like the end of the book is a little bit more downbeat," Dunham told the audience during a Q&A after the film's debut. "Birdy is in a little bit more of a compromised situation, and I just felt like I could not put the audience through falling in love with Bella [Ramsey, who plays the character] for two hours and then leave her in a place where we were afraid for her."

She continued, "So that was a shift, but luckily I had the blessing of the author and the blessing of everyone around me, and I'm ultimately so grateful for all of these guys."

ALEX BAILEY/Prime Video Andrew Scott and Bella Ramsey in 'Catherine Called Birdy'

The details of that updated ending won't be revealed here, but like the book, the film is set in medieval England, and follows 14-year-old Birdy as she navigates through life avoiding the many potential suitors her father (played by Andrew Scott) has in mind for her. Billie Piper, Joe Alwyn, Isis Hainsworth, and Sophie Okonedo also star in the film.

Catherine Called Birdy debuts in select theaters on Sept. 23, followed by its Prime Video streaming premiere on Oct. 7.

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