Justin Bieber: I don't know why Prince William doesn't take hair loss pills
The teen singer reckons Wills, 30 - who's going a little thin on top - should use controversial hair loss tablets that are available in his native Canada.
'I don't know why he doesn't just get those things, those products,' Justin, 18, tells Rollacoaster magazine.
'You just take Propecia and your hair grows back. Have you not got it over here?'
But William is going to be a little too busy to worry about his thinning crown for the forseeable future.
He and his wife Kate Middleton, also 30, have announced plans to visit the world's oldest rainforest when their Diamond Jubilee tour takes them to the island of Borneo in September.
They'll also fly to Singapore, the Solomon Islands and Tuvalu, which is the world's 4th smallest country.