David Foster's ex-wife Linda Thompson is worried about his age gap with Katharine McPhee

Linda Thompson has an opinion on ex-husband David Foster’s new engagement to Katharine McPhee.

“I wish them well,” Thompson, 68, told Us Weekly on Saturday. “I think the only thing that’s a real deterrent, I think, is the age difference.”

Foster is 68 and McPhee is half his age at 34.

Thompson and Foster were married in 1991 and divorced in 2005. Their 14-year-marriage did not produce any children.

Foster and McPhee got engaged earlier this month while vacationing on the Italian island of Capri.

“But I think life doesn’t have any guarantees anyway,” Thompson, who is a Grammy-nominated songwriter, added. “If you find someone you love, go for it, you know? [McPhee is] is a lovely person. She’s beautiful and she’s talented, and they have that musically in common, so that goes a long way.”

Since popping the question, Foster and McPhee have stayed relatively quiet. But Foster did express his happiness telling Access Live, “We’re all happy. And you know, for someone reason, the two of us, one plus one makes for four instead of two. So it seems like it’s interesting news to people, so we’re just gonna roll with it.”

Foster first met McPhee back in 2006 when she was a contestant on “American Idol."

This article originally appeared on Page Six.