React PropTypes: Allow different types of PropTypes for one prop

I have a component that receives a prop for its size. The prop can be either a string or a number ex: "LARGE" or 17.

Can I let React.PropTypes know that this can be either one or the other in the propTypes validation?

If I don’t specify the type I get a warning:

prop type size is invalid; it must be a function, usually from
React.PropTypes.

MyComponent.propTypes = {
    size: React.PropTypes
}