Sienna Miller revealed that Chadwick Boseman sacrificed a portion of his pay from "21 Bridges" to make sure she is in the movie.

Boseman acted in and produced the big-budget film and was determined to cast the "American Woman" star. The actress revealed that he approached her for the role of detective Frankie Burns. He was "really active in trying" to get her to do it.

However, at the time, Miller was hesitant to return to acting. She wanted to rest because she "had been working non-stop" and she was exhausted. But a part of her also wanted to work with him.

"He was a fan of my work, which was thrilling, because it was reciprocated from me to him, tenfold. So he approached me to do it, he offered me this film, and it was at a time when I really didn't want to work anymore," the 38-year old told Empire Online.

Then there was also the matter of the pay. Miller shared that she asked for a certain number and made a deal to appear in "21 Bridges" only if they agreed to the amount.

"I didn't know whether or not to tell this story, and I haven't yet. But I am going to tell it, because I think it's a testament to who he was," she said.

"This was a pretty big-budget film, and I know that everybody understands about the pay disparity in Hollywood, but I asked for a number that the studio wouldn't get to. And because I was hesitant to go back to work and my daughter was starting school and it was an inconvenient time, I said, 'I'll do it if I'm compensated in the right way,'" Miller recalled and revealed that Boseman ended up taking a pay cut.

The "Black Panther" star let go of some of his salary to get to the amount Miller asked for. He even agreed that it was what she deserved to be paid. The "American Sniper" star praised Boseman and said that it was "the most astounding thing" that she has ever experienced.

"'You're getting paid what you deserve, and what you're worth.' It's just unfathomable to imagine another man in that town behaving that graciously or respectfully," Miller remarked.

She said she told her male actor friends about what Boseman did and "they all go very very quiet and go home and probably have to sit and think about things for a while." Miller remembered that "there was no showiness" when he did it.

Golden Globes 2017
Sienna Miller arrives at the 74th Annual Golden Globe Awards in Beverly Hills, California Mike Blake/Reuters