Josh Brolin expecting daughter with wife Kathryn

May 29 (UPI) -- Josh Brolin and his wife are expecting a baby girl.

The 50-year-old actor announced in an Instagram post Tuesday that Kathryn Brolin is pregnant with their first child together.

Brolin shared a slideshow of photos from a hike with Kathryn. The mom-to-be showed off her baby bump in a cropped tank top and leggings.

"There's a new sheriff in town, and she's no bigger than a sweet potato. Hang on to your hats. #jbkstucktogether #lilbeanterritory #loveisaslovedoes," Brolin captioned the post.

Kathryn, Brolin's former assistant, also shared the news on her own account.

"Something's cookin... Baby Girl Brolin on the way #jbkstucktogether #loveisaslovedoes," she wrote.

Brolin is already parent to 29-year-old Trevor and 24-year-old daughter Eden with first wife Alice Adair, and was also married to Diane Lane. He wed Kathryn in September 2016 after more than three years of dating.

"You are the completion of any and everything that was ever incomplete in me. I love you from here to Timbuktu," the star gushed in a post to Kathryn on Valentine's Day in February.

Brolin recently played Thanos in Avengers: Infinity War and Cable in Deadpool 2, and will reprise Thanos in an Avengers sequel. He will star in the Sicario sequel Sicario: Day of the Soldado.