LVMH boss Bernard Arnault raised his job's retirement age to 80. Warren Buffett told him that age limit was too low.

• Warren Buffett wrote to Bernard Arnault after the LVMH CEO raised his job's retirement age to 80.
• The investor suggested that the luxury tycoon should have lifted it, Bloomberg reported.
• Berkshire Hathaway's 93-year-old CEO has argued that great bosses only get better with age.

After Bernard Arnault raised the retirement age for his job to 80 from 75 in 2022, Warren Buffett wrote to the luxury tycoon suggesting he should have hiked it.

Bloomberg reported this week that the famed investor and Berkshire Hathaway CEO wrote a letter to the LVMH CEO "telling him he made a mistake by setting the new age limit so low."

Buffett, 93, might be proved right. Arnault, 75, doesn't expect to retire anytime soon. "I don't think he'll ever stop," one of his sons told Bloomberg.

Like Buffett, Arnault reportedly loves what he does, takes pride in building one of the world's largest companies, and feels a duty to protect its legacy and continuity when he hands it off to the next generation.

The two men have plenty more in common. They both rank among the world's richest people , with fortunes in excess of $100 billion, and they're both running public companies into old age.

Moreover, they've built sprawling conglomerates that are home to dozens of independent, autonomous subsidiaries. LVMH's brands include Louis Vuitton, Moët & Chandon, Hennessy, Christian Dior, Sephora, and Tiffany & Co. Berkshire's businesses include Geico, Dairy Queen, Duracell, and Jazwares, the maker of Squishmallows.

Close followers of Buffett won't be surprised to learn of Buffett's comment to Arnault. The Berkshire chief's opinion has long been that great managers are like fine wines — they only improve with age.

"Buffett's view is that high-quality people like those on his board and running his companies get better with time and experience and so should not face mandatory retirement," Larry Cunningham, a professor emeritus of law at George Washington University who wrote the book "Berkshire Beyond Buffett: The Enduring Value of Values," told Business Insider.

Indeed, only one of Berkshire's 14 directors is younger than 60, and six are older than 70, per the company's most recent proxy filing . Charlie Munger, Tom Murphy, Walter Scott, and David "Sandy" Gottesman all sat on the board into their 90s.

Buffett "has often joked that his death is far in the future," Cunningham said. The author noted that the investor once quipped to CNBC that 103 was the "yardstick" for retirement at Berkshire, as one of his top lieutenants, known as Mrs. B, stepped down at that age.

Buffett has also joked that he might give Methuselah — the biblical figure who supposedly lived to 969 — a run for his money.

"On the other hand, he joked at this year's meeting about his own age, that he reads the mortality tables and knows his time is short," Cunningham added.

Buffett has set the high-water mark for CEO longevity, and his letter to Arnault signals that he thinks the LVMH boss can handle a lot more wear before he needs replacing.