Bradley Cooper banned Lady Gaga from doing one thing while filming “A Star Is Born,” and it was a rule that Lady Gaga had a hard time following. In an interview, the popular duo talked about the making of “A Star Is Born” and how one rule set by Cooper made Lady Gaga feel so insecure about herself.

Cooper starred in the film alongside Lady Gaga, but he also directed it. While talking about their film on the Graham Norton Show, Lady Gaga revealed that Cooper strictly banned her from wearing makeup during filming because he wanted her to be just “how the character is.”

Cooper maintained that the rule had nothing to do with Lady Gaga. All he wanted was for her to appear in the film barefaced because that was what her role required.

While a makeup ban sounds easy for some, for Lady Gaga, it doesn’t. The female singer admitted that she struggled with the ban, especially since she’s used to wearing makeup every time. Lady Gaga even admitted trying to sneak makeup on the set of “A Star Is Born” because she could not stand appearing in the film without any makeup on her face.

“It put me in the right place I needed to be, because when my character talks about how ugly she feels — that was real,” Lady Gaga said. “I’m so insecure … I like to preach, but I don’t always practice what I preach,” she added.

Lady Gaga revealed that Cooper even used a makeup remover on her face during her screen test to make sure that she was not wearing any makeup while filming. “Completely open,” Cooper told her. “No artifice.”

The actor-director was so strict that even her attempts at secretly putting some light makeup on didn’t work. “I tried to sneak some make-up in, but Bradley wouldn’t go for it,” she said.

A remake of the 1937 classic, “A Star Is Born” centers on a country singer-songwriter who falls in love with a struggling nightclub performer. According to Lady Gaga, being part of the film was a dream come true for her.

Bradley Cooper and Lady Gaga In this handout provided by A.M.P.A.S., Bradley Cooper and Lady Gaga perform onstage during the 91st Annual Academy Awards at the Dolby Theatre on February 24, 2019, in Hollywood, California. Matt Sayles - Handout/A.M.P.A.S. via Getty Images