"I mean, there are things to prevent that nowadays, like Propecia," Bieber, 18, told the U.K.'s Rollercoaster magazine about the 30-year-old royal's thinning hair. "I don't know why he doesn't just get those things, those products. You just take Propecia and your hair grows back. Have you not got it over here?"
Not surprisingly, Brits are taking the "Boyfriend" singer's careless remark about their future King as a national affront.
PHOTOS: Prince William's funniest quips
U.K. citizens "are viewing Justin Bieber's diss about Prince William's challenging hair problem in the same way you view an annoying fly buzzing around you. He needs to be swatted away," British journalist Jessica Callan told The Huffington Post. "Wills and Prince Harry may joke about William's thinning hair, but that doesn't mean a kid like Justin can come sauntering in and join in the joke."
Tell Us: What do you think of Bieber's hairy counsel? Did he go too far?
Not surprisingly, Brits are taking the "Boyfriend" singer's careless remark about their future King as a national affront.
PHOTOS: Prince William's funniest quips
U.K. citizens "are viewing Justin Bieber's diss about Prince William's challenging hair problem in the same way you view an annoying fly buzzing around you. He needs to be swatted away," British journalist Jessica Callan told The Huffington Post. "Wills and Prince Harry may joke about William's thinning hair, but that doesn't mean a kid like Justin can come sauntering in and join in the joke."
Tell Us: What do you think of Bieber's hairy counsel? Did he go too far?