US Actor Ashton Kutcher, 34, is reportedly so serious about new girlfriend, US actress Mila Kunis, 28, that he's already planning marriage and babies.

The former That '70s Show co-stars have been living together and recently took a vacation to Bali.

Asource told OK! magazine: "Ashton feels his biological clock ticking. He's wanted kids for years, but he and (former wife) Demi (Moore) didn't have luck conceiving, most likely because of her age...

"Ashton has told his close friends and family members that he's madly in love and wants to marry (Mila). And he's been on a campaign to get her to agree to become a mum."

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