A mini-mountain is on the way!

Hafþór Júlíus Björnsson, who played Ser Gregor Clegane — aka “The Mountain” — on Game of Thrones — and wife Kelsey Henson are expecting a baby boy, the actor announced on Friday, along with photos from their “gender reveal” party.

The actor, 31, and his wife, 30, learned the sex of their first baby by popping a large black balloon which then burst with blue confetti inside.

“Swipe right to see gender of the mini me! 😱,” Björnsson wrote alongside a series of photos that showed the parents-to-be beaming with joy.

Never miss a story — sign up for PEOPLE’s free daily newsletter to stay up-to-date on the best of what PEOPLE has to offer, from juicy celebrity news to compelling human interest stories

Björnsson and Henson, who are 6-ft. 9-in and 5-ft. 2-in. respectively, showed off their excitement with their hands in the air, smiling from ear to ear.

In another photo, the two share a sweet kiss and are seen looking lovingly at one another after finding out the big news.

Henson also shared the exciting moment on her own Instagram.

RELATED: ‘The Mountain’ from Game of Thrones Marries Girlfriend Kelsey (She’s 5-ft. 2-in.!)

Júlíus Björnsson/Instagram

The GoT star and Henson tied the knot in October 2018 in Iceland.

“It is with great pleasure that I now get to call Kelsey Morgan Henson my wife!” he captioned a photo of himself holding his bride up on their wedding day.

RELATED: Welcome to the World! See All of the Celebrity Babies Born in 2020

“I get to hold this beautiful woman through thick and thin for the rest of our lives!” he continued. “I’m so excited for all of the future adventures we will tackle side by side. @kelc33 #justmarried.”

Story continues

The two have been dating since September 2017. According to TMZ, they hit it off after she asked for a picture with him at a bar in Alberta, where she was working at the time. Björnsson was in town for a Strongman competition.

Björnsson previously dated Andrea Sif Jónsdóttir, an engineering student, and has a daughter from a previous relationship.

He won the World’s Strongest Man competition in the Philippines in May 2018.