How can I get the musty smell out of an old pair of shoes?

I’ve “rescued” a pair of shoes from the back of a cupboard, where they’ve been sitting in a plastic bag for probably three years. They’re still in decent condition and they’re perfectly dry and not mouldy, but there is a musty smell about them that I want to get rid of before I wear them again. How can I get rid of it?

The shoes have leather uppers, rubber soles and synthetic lining.