Hilary Duff says she is ready to add 'one more to this crazy' family as she is expecting a fourth child

LOS ANGELES, CALIFORNIA: Hilary Duff has delighted her fans by announcing on Instagram that she and her husband Matthew Koma are expecting their fourth child.

The 36-year-old singer also unveiled a heartwarming family holiday card that featured her children and Koma as the soon-to-be family-of-six posed in a bedroom.

Hilary Duff's festive card says 'so much for silent nights'

In the festive photo, Duff could be seen looking shocked and placing her hand on her baby and captioned, "Surprise Surprise!."

Her four-year-old daughter Banks playfully hung from the bed's rafters while Duff's two-and-a-half-year-old daughter Mae is seen sitting on the ground with a guitar.

The 'Lizzie McGuire' alum's 11-year-old son who is holding a video game controller is also seen sitting in an armchair while Koma struck a pose on the bed with one raised eyebrow. "So much for silent nights. Love, the Duff-Bair-Comrie Crew," read the card.

The former Disney star shared the back of their festive card which featured solo images of all three of her children. "Buckle up Buttercups, we're adding one more to this crazy bunch!" read the other side.

Koma also shared the joyous news on social media as he reposted the family's holiday snapshot on Instagram and wrote, "Baby #4 is loading..." as he tagged the location of his picture as "Vasectomy clinic."

Hilary Duff says she 'loves this mayhem' of being a mother-of-three

Duff shares her son Luca with her ex-husband and her two daughters with Koma. Speaking to People about how she enjoys her life as a mother of three, the 'Elixir' author said she "loves this mayhem."

"I'm so in love with all my kids. It's a learning curve to throw a newborn into the mix," the actress referred to her daughter Mae.

"A lot of people have been like, 'That third kid really gets you.' And they're right!", she added.

Hilary Duff says Matthew Koma is an 'amazing dad right out the gate'

Duff reflected on Koma taking up the amazing role as a father of her children as she said, "he was such an amazing dad right out the gate."

"In this time of breastfeeding and craziness, he was like, 'I'm just going to be your assistant because I think that's how I'm going to be the most help to you in this timeframe,'' she added.

"He has this really amazing way of looking at the big picture where I'm very much like, right-here-right-now — and he zooms out," she said of Koma whom she met during the collaboration of her 2015 album 'Breath In Breath Out.'