Lionel Richie refuses to be called grandpa and has revealed the sweet name daughter Sofia Richie's baby girl will call him.

The 74-year-old singer's youngest daughter Sofia, 25, is expecting her first child with husband Elliot Grainge, 30, and Lionel couldn't be more thrilled for the couple.

He gushed to 'Entertainment Tonight': "My baby is having a baby, and I'm so thrilled for Elliot and Sofia. They are just over the moon."

However, the little one won't have a traditional name for her grandparent, with Lionel revealing he will be known as "Pop-pop."

The 'Hello' hitmaker also revealed he keeps telling the couple to keep some privacy after they revealed the unborn tot's gender to the world with a pink confetti cannon.

He said: "You know, there is no secret with those two! I keep saying, 'Keep it a secret, OK?' But yes, that's what's happening. I'm so happy."

Sharing his nickname for his grandchildren, he said: "I'm Pop-pop.

"We don't get the 'grandpa,' yeah, that's a little deep. Pop-pop is where we're going."

Lionel is also a father to adoptive daughter Nicole, 42 - who has Harlow, 16, and Sparrow, 14, with husband Joel Madden - as well as Miles, 29, with ex-wife Diane Alexander.

Model Sofia - who tied the knot with music executive Elliot last April - is six months pregnant but only announced the news on January 26, and explained that she had kept the news to herself for so long in an attempt to "protect" both herself and her spouse.

She told Vogue: "Pregnancy is really scary and you want to protect that space. I didn’t realise there are so many milestones you have to hit and so many tests you have to take. For me, it was really important to protect our mental health and our space as a couple.”