Taking to the photo-sharing app, Mario proved Giovanna and her husband McFly star Tom Fletcher really don't have long until they welcome baby number two.
He told fans: "Not long now!!!!! Niece/Nephew imminent."
In his photo, Mario can be seen placing a protective hand on Giovanna's bump. She looks almost ready to pop, right?
He shared a heart-eyed emoji alongside his snap, suggesting he can hardly wait to meet the Fletcher's new arrival. Mario's fans, meanwhile, shared their thoughts on whether Giovanna is having a boy or girl.
Despite her due date fast approaching, Giovanna still hasn't shared the sex of her baby and it seems Mario's fans are completely torn.
While many suggested Giovanna is having another boy, others commented that they think it could be a girl this time round.
One user said: "I hope it's a girl." While another predicted: "It's [a] bigger bump [than] buzz so I think it team pink."
Giovanna and Tom first announced they are becoming parents again back in September. Of course, they chose to announce their baby news in the coolest way.
Tom, Giovanna and their now one-year-old son Buzz starred in a professional looking YouTube video that saw the McBusted singer uncover a MegaDrive console in his attic.
While Buzz is revealed as player one, player two is then uncovered as a baby scan resting on Giovanna's stomach.
Speaking to Reveal ahead of his bubba's arrival, Tom told us: "We really don't mind if it's a girl or a boy. I had the best relationship with my sister growing up so a sister for Buzz would be lovely. He can't wait to be a big brother!"
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