Credit: Gilbert Carrasquillo/GC Images

Last year, Emmy Rossum made headlines when she won equal pay after demanding to earn the same amount as her Shameless co-star William H. Macy, who plays troubled dad Frank Gallagher on the Showtime drama about a dysfunctional family of six kids struggling to raise themselves without a mother.

Now entering production for her eighth season with the show, the actress—who stars as the oldest daughter and unofficial family matriarch Fiona in the series—is opening up about why she decided to go up against the series' producers and demand equal pay.

When asked about her motivations to pursue a salary raise during her Vulture Festival panel appearance, along with co-star Macy and executive producer Nancy Pimental, the Phantom of the Opera alum said that she'd originally been hesitant to broach the subject for other reasons.

"When the show started, Bill was one of the first people attached. I was the last piece in the puzzle and I'd never done TV before, and I obviously wasn't as well known, while Bill is an Oscar nominee," she said. "So for the first few seasons, a difference made a lot of sense."

The 30-year-old continued, "As the time went on, the leadership role started to feel somewhat more shared," explaining that both she and Macy had directed on the show.

"I felt that I loved the show, that I loved everyone in it, but I just wanted it to feel right," she said.

WATCH: Emmy Rossum's Gorgeous Cover Shoot

When it came time to approach the director and the people behind the show, Rossum remembered receiving an overwhelming amount of support from her co-star, which he reiterated during his panel appearance.

"It's show biz's job to get us for as cheaply as they can—and our job to say no," the Fargo star said, citing his "no-brainer" decision to back Rossum. "It's unconscionable they would pay a woman less for the same job."

Watch Rossum talk about her decision to pursue equal pay in the video below.