Halle Bailey's Little Mermaid co-star Melissa McCarthy gave her advice on how to stick up for herself

When Halle Bailey stepped into Ariel's shoes - or tail, rather - it was a huge deal.

Not only did Disney give fans the first live action Little Mermaid but, in casting Halle, they brought the first ever Black Ariel to life.

That's a lot for a 22-year-old to take on, but when things got a little overwhelming on-set, Halle says her co-star Melissa McCarthy was her saving grace.

In the upcoming Disney flick, Melissa McCarthy plays Ursula the Sea Witch, who offers to give Ariel legs in exchange for her voice.

Melissa may have been vengeful, cruel and wicked on-camera, but behind the scenes she was always on hand to help Halle through the tougher days.

In an interview with CNN, Halle explained that on a major set like The Little Mermaid, 'a lot of the time it can be scary and intimidating' to speak up for herself.

Meanwhile, it was 'really cool' to watch McCarthy 'come onto set and be just so comfortable with who she was in her skin and [to see] her standing up for herself.'

But Melissa assured her that it wasn't always so simple.

Explaining how the Gilmore Girls star was able to help guide her through it all, Halle continued: “She was telling me, ‘Yeah, I had to learn. I wasn’t always this way, and when you’re young, you’re timid.'"

She added that Melissa told her that it wasn't until she got older that she learned how to 'speak up and [say] what works for' her.

Melissa's advice was a godsend to Halle, who admitted she definitely had moments where she needed to speak up for herself or take some time to 'clear [her] head.'

In another recent interview, Halle revealed that she was in the water for 13 hours for some days on set.

"I pushed myself as far as I’ve ever pushed myself in life," she told Edition.

"And I feel like the message from her was to know that you've always had it in you."

Elsewhere in the interview, Halle revealed how this new live action will tell a new, more modern version of the classic fairytale.

"I'm really excited for my version of the film because we've definitely changed that perspective of just her wanting to leave the ocean for a boy," she said.

"It's way bigger than that. It's about herself, her purpose, her freedom, her life and what she wants."

The Little Mermaid is set to hit theatres on 26 May.