Jessica Chastain is sick of getting paid less than her male co-stars and she's not going to take it anymore. She's become an outspoke advocate for equal pay in Hollywood, but how does one undo decades of ingrained sexism in an industry where male actors regularly make more than their female counterparts? It's quite simple. Jessica Chastain simply asks to know how much her male co-stars are making up front.

The Academy Award nominee suggested in 2015 that she earned less than $2 million to co-star in The Martian with Matt Damon, who took home $18 million. In a new essay for Variety, she shares how she now makes sure similar situations don't happen again in the future.

It all started when she once heard former Sony studio chief Amy Pascal say that often actresses just don't ask for as much money as their male counterparts, and that's when it clicked for Chastain.

"That really hit me. At first, I was really pissed off. And then I thought, 'She’s touching on something here,'" she wrote. "Women need to step forward and demand they’re fairly compensated for their work."

Chastain also reveals that in the past studios have come to her to star in a film first, but then will find a male co-star next, negotiate his deal, and then offer her whatever was left over.

No more of that, says Chastain.

"What I do now, when I’m taking on a film, I always ask about the fairness of the pay," she writes. "I ask what they’re offering me in comparison to the guy. I don’t care about how much I get paid; I’m in an industry where we’re overcompensated for the work we do. But I don’t want to be on a set where I’m doing the same work as someone else and they’re getting five times what I’m getting."

It's not bad advice. One of the most egregious tales of unequal pay in Hollywood revealed recently was the fact that Ashton Kutcher was paid three times as much for No Strings Attached as Natalie Portman. This despite the fact that the film definitely benefited form the buzz of Portman's then recent Academy Award win, and that Portman has continued a career in film while Kutcher now mostly concentrates on television.

Portman revealed that at the time she wasn't as "pissed" as she should have been, and was just grateful to be making so much money for a film role in the first place, but has since realized she probably shouldn't have been.

For her part, Chastain revealed that she has lost one major role due to her new negotiating tactics, but otherwise she seems to be doing fine.

She's attached to several upcoming projects with high profile male costars. She'll appear in action thriller The Division with Jack Gyllenhaal, the aptly titled Woman Walks Ahead with Sam Rockwell, Molly's Game with Idris Alba and Kevin Costner, and George and Tammy with Josh Brolin. She's also attached as the lead for Painkiller Jane, and is actually teaming up with Portman for Xavier Dolan's The Death and Life of John F. Donovan with a female-heavy cast that also includes Bella Thorne, Susan Sarandon, Thandie Newton and Kathy Bates.

Presumably, she's getting properly compensated for all projects now.

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