Updated

`Studio 60' actress Amanda Peet says she's pregnant and plans to marry this weekend

Amanda Peet and screenwriter David Benioff are expecting a baby and will marry this weekend, the "Studio 60" actress says.

Peet, 34, told David Letterman on CBS' "Late Show" on Wednesday that she is four months' pregnant, earning her the nickname "Fatty" on the set of her NBC show.

"See, that's not right," Letterman said. "That's just not right."

"I think it's really funny," she replied.

Peet starred in the movies "Something's Gotta Give, "Syriana" and "The Whole Ten Yards," opposite Matthew Perry, her co-star on "Studio 60 on the Sunset Strip."

Benioff's screenwriting credits include "25th Hour" and "Troy."