Mel Gibson may be expecting his ninth child, but fatherhood is still pretty tricky for the seasoned parent

By Char Adams
November 01, 2016 10:21 AM

Mel Gibson is expecting another child, and the star says being a new father — yet again — is taking a toll on his body.

“I’ve got stretch marks, man,” the 60-year-old actor joked during a Tuesday appearance on Good Morning America. “I got stretch marks.”

Quipped Michael Strahan, “That happens after you get past five.”

The actor is expecting his ninth child with his girlfriend of two years, Rosalind Ross. The baby will be Ross’ first.

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Gibson’s rep confirmed the baby news to PEOPLE in September. And a source said that the Machete Kills star is stoked to add to his already sizable brood.

“Mel and Rose are so excited about the baby,” a friend close to the couple tells PEOPLE. “Mel loves being a dad and he and Rose can’t wait to be parents together. The last two years have been some of his happiest years he’s ever had.”

RELATED VIDEO: Mel Gibson and Girlfriend Rosalind Ross Are Expecting Their First Child

Gibson took to the morning show to discuss his new film Hacksaw Ridge and the pros of working with his son Milo on the movie. But the father-son collaboration hasn’t been all rainbows and sunshine.

“He doesn’t listen to me. He never has. Why should he start now?” Gibson said when Strahan asked whether the 26-year-old takes direction from the seasoned star.

“I give him suggestions. I find that kids — especially when they’re teenagers — if you keep talking at them, you find out that they heard everything later.”

Milo Gibson, Mel Gibson

Milo Gibson and Director Mel Gibson seen at Summit Entertainment, a Lionsgate Company, Los Angeles Special Screening of “Hacksaw Ridge” after party at The Academyís Samuel Goldwyn Theater on Monday, Oct. 24, 2016, in Beverly Hills, Calif. (Photo by Eric Charbonneau/Invision for Lionsgate/AP Images)

He added, “They scare you to death, and then you find out it all resonated at some point.”

Hacksaw Ridge, in which Milo stars, chronicles the true story of Virginia-farm-boy-turned-Army medic Desmond Doss, played by Andrew Garfield, who was credited with saving dozens of soldiers during the Battle of Okinawa, despite refusing to carry a weapon or kill his enemies.

The film marks Gibson’s return to the director’s chair after nearly 10 years.

Hacksaw Ridge hits theaters Friday.