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Dermot Mulroney's rakish grin has graced the big screen in more than 65 films, but it would not be the same without that familiar scar just above his lip.

Now, the 50-year-old actor reveals how he got it.

"It was a long time ago, so I've always had it," he told the Chicago Sun-Times' Splash magazine. "I was 3 1/2 and I was carrying a dish for our pet rabbits. And I tripped and it broke, and I fell on it."

Mulroney added: "I definitely remember that day, even though I was 3 years old. I don't think about it or see it, but it's always been there. It certainly has its place on my face, right below my right nostril. That's where it belongs."

Mulroney is currently filming in Chicago for his latest role in the NBC series "Crisis," in which he plays the creepy Francis Gibson, whom he describes as a "seemingly mild-mannered ex-CIA analyst who's a chaperone and parent" on a hijacked bus filled with the children of Washington's elite.

Dermot Mulroney Reunites with Julia Roberts in 'August: Osage County'

The Windy City is familiar territory for the former Northwestern University student who got his big break in Chicago starring opposite Julia Roberts and Cameron Diaz in 1997's "My Best Friend's Wedding."

"It's its own phenomenon in that it's remained as popular as it ever was," Mulroney told Splash about the classic romantic comedy. "It's dropping into a short list of romantic comedies that will last forever."

Since then, Mulroney has starred alongside Jack Nicholson in 2002's "About Schmidt" and Liam Neeson in the 2011 thriller "The Grey," and appeared on the small screen in "New Girl" and HBO's "Enlightened."

Last year, he reunited with Roberts in "August: Osage County," playing Juliette Lewis' sleazy fiance.

"I tried really hard to get that part," he told Splash. "Julia and I were very thrilled."