Fergie's son dresses up as Harry Potter on her birthday

March 28 (UPI) -- Fergie's son celebrated her 43rd birthday by dressing up as Harry Potter.

Fergie said in an Instagram post Tuesday that she spent the occasion with her "most magical" gift, 4-year-old son Axl Jack, whom she shares with ex-husband Josh Duhamel.

The singer shared a photo of Axl wearing a Hogwarts School of Witchcraft and Wizardry uniform, round eyeglasses and a painted-on lightning bolt-shaped scar. The 4-year-old completed his look with a toy wand.

"my most magical birthday gift ever #AxlJack," Fergie captioned the picture.

Fergie said in an interview with Entertainment Tonight in January that Axl is "a ham" like Duhamel.

"Yes, he is a ham, I think just like his dad, and maybe his mom, I don't know," the star said. "I'm just so serious all the time."

"He loves to laugh, he loves to have fun," she added. "Anything Boss Baby is just -- that's on repeat at our house."

Fergie announced her split from Duhamel in September after eight years of marriage. She said the same month that she and the actor remain "great friends" and focused on raising Axl.

"There's so much love that we have for each other," the singer told Entertainment Tonight. "We really like each other, we have fun with each other."

"We're just not a romantic couple anymore," she explained. "But we are still Axl's parents through and through."