The CEO of Levi’s, Chip Bergh, is revealing the secret for all lovers of jeans. If consumers really want them to last, just don’t wash them.

Berg advised people not to wash their jeans while speaking at Fortune's Brainstorm Green conference in Laguna Niguel, Calif. this week. In fact, he said he hasn’t washed the jeans he wore to the conference in a year.

"These have yet to see a washing machine. I have yet to get a skin disease or anything else," he explained to Fortune.
He also talked about sustainability, saying Levi’s jeans are the most popular brand in second hand stores.

"We are the ultimate in sustainable apparel. If you buy [our jeans] they will last a lot longer than most people's waistlines will,” said Bergh, USA Today reports.

Tuesday, May 20 marked a milestone for Levi’s Straus – it marked the 141st birthday of the brand’s 501 jean.