Josh Brolin and wife Kathryn Boyd are having another baby.

Boyd, 32, announced Tuesday that she is expecting her second child with 52-year-old Brolin.

“The Brolin’s are a growin’!!,” the model captioned a pic on Instagram showing off her growing baby bump. “Our little December babe is on the way…. .”

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Brolin jokingly responded by commenting, “Wow. That’s amazing! Congratula…wait…WHAT?!?!”

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The couple are the parents of 19-month-old daughter Westlyn.

They got married in North Carolina in September 2016 after dating for three years.

LOS ANGELES, CALIFORNIA - FEBRUARY 21: (L-R) Josh Brolin and Kathryn Boyd arrives at the 2019 Hollywood For Science Gala at Private Residence on February 21, 2019 in Los Angeles, California. (Photo by George Pimentel/Getty Images)

The “Avengers: Endgame” actor is also father to daughter Eden Brolin, 26, and son Trevor Brolin, 32, whom he shares with ex-wife Alice Adair.

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He was also previously married to actress Diane Lane, though they had no children together.