Hollywood couple Ashton Kutcher and Mila Kunis are reportedly expecting their second child together.

PEOPLE magazine, citing a "source", said the That 70s Show pair - who already have a daughter, 20-month-old Wyatt Isabella - were expanding their family, and said Kutcher "lights up" whenever he talks about the new arrival.

The couple married in secret in July last year, and have spoken openly in the past about their desire for more children.

"Ashton genuinely lights up when talking about Wyatt and the little one on the way," a source told PEOPLE.

"Everything about being a father is natural to him."