“The Gilded Age” Star Morgan Spector Wears 'Bertha' Shirt, and Not Much Else, in Revealing Gym Selfie - See the Photo

The actor ribbed his on-screen wife, Carrie Coon, during a workout

Fans of The Gilded Age aren't used to seeing star Morgan Spector so dressed down!

The actor, 43, is normally suited up from head to toe as ruthless industrialist George Russell in the Max period drama set in 1880s New York. The Russells represent new money, which doesn't sit well with the established elite.

Carrie Coon, 41, portrays George's social-climbing wife Bertha, and Spector playfully paid homage to his costar in his latest gym selfie.

In a photo uploaded to his Instagram story on Wednesday, a sweaty Spector is seen wearing a t-shirt emblazoned with Bertha's name and face - and little else.

"@carriecoon without socks it just wasn't elegant enough," Spector tagged his costar.

The actor flexed his quads below what we hope are very short shorts.

The Gilded Age is a favorite among fans of period dramas and was created and written by Downton Abbey's Julian Fellowes.

Unlike Downton Abbey, The Gilded Age is set in America - specifically New York City - though many of the scenes are shot in New England.

Related: Where Is 'The Gilded Age' Filmed in Newport? Location Manager Shares the Real Places (and Which They Faked)

"There's a big overlay of the New York and Newport locations," location manager Lauri Pitkus told PEOPLE last November. "Because we have these beautifully appointed, unique and original bedrooms to choose from, we shoot most of those in Newport and cheat them for existing in the New York houses."

In addition to the stately mansions, viewers are also drawn to the lavish costumes. For the female cast members, that involves wearing waist-cinching corsets.

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"It was taxing physically and mentally, I couldn't sleep on my side for a long time because my ribs were so sore," actress Louisa Jacobson, who plays Marian on the show, explained. "That's when I realized I really need to loosen this up. After every take or between setups, I would ask my dresser to untie the corset so that I could get a break. They were called corset breaks."

Now with Spector's revealing Instagram post, viewers know what lies beneath George Russell's expertly tailored suits and tuxes, too!

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