Matthew McConaughey married Camila Alves after their son convinced them to tie the knot with a very candid question.

During Monday’s episode of the “Modern Wisdom” podcast, the actor shared that his son Levi was just 4 years old when he asked why his mom didn’t have the same last name as his dad.

“I’m going through my head, ‘You’re f–king 4, dude,’” McConaughey recalled. “I sat there. I was like, ‘It’s a great question, but I mean, we’re not married. When you get married, you switch your name.’”

The actor said Levi — now 17 years old — just “sat there and listened” before asking his father if he was “scared” to take the plunge.

“I’m like, ‘You’re f–king 4 years old, dude.’ And I was like, ‘Yeah, I guess I am,’” he said.

McConaughey’s conversation with his inquisitive child led to the Academy Award winner turning to his pastor for advice.

“My pastor goes, ‘Let me just ask you this, Mr. Risk Taker. What’s the bigger risk? Carrying on like you’re going and it’s going well, or taking the deeper dive into the sacramental covenant of marriage?’” he said.

McConaughey — who also sought counsel from other “elder men who had long-term relationships, who were married for decades” — remembered telling his pastor that marriage would be the bigger risk.

The “How to Lose a Guy in 10 Days” actor, 55, and Alves, 42, met at a Los Angeles nightclub in 2006. They quickly fell for each other and confirmed their relationship a year later.

In 2008, the duo became parents for the first time when the model gave birth to Levi on July 7, 2008. They went on to welcome their second child, daughter Vida, in 2010.

A year later, McConaughey proposed to Alves and they finally said “I do” in 2012. In late December of that year, they welcomed their third child: son Livingston.

The couple has since continued to foster a strong marriage, with McConaughey frequently praising his wife for her support.

McConaughey revealed the secret to their successful marriage in his new book, “Poems & Prayers,” which was released Sept. 16.

“The best thing you can / do for your / marriage,” he titled one entry, before diving in, “One way to surely / get ahead / is get rid of that / king-­size mattress / and sleep in a / queen-­size bed.”

He reflected on their decision to downsize to a smaller bed in an interview with Fox News Digital earlier this month.

“I wake up one morning … I’m looking over there and Camilla’s like a football field away man,” he said. “Then you go to bed at night, like you want to snuggle up and …’Well, we’ve got to cover you up. Come about 12 feet and I’ll come 12 feet.’”

This is when he realized their massive mattress was “not good for the marriage.”

“Get rid of that son of a bitch,” he exclaimed. “So we got a queen size where we’re shoulder to shoulder. I’m telling you, it’s good for your marriage.”