How to specify (optional) default props with TypeScript for stateless, functional React components?

I'm trying to create a stateless React component with optional props and defaultProps in Typescript (for a React Native project). This is trivial with vanilla JS, but I'm stumped as to how to achieve it in TypeScript.

With the following code:

import React, { Component } from 'react';
import { Text } from 'react-native';

interface TestProps {
    title?: string,
    name?: string
}

const defaultProps: TestProps = {
    title: 'Mr',
    name: 'McGee'
}

const Test = (props = defaultProps) => (
    <Text>
        {props.title} {props.name}
    </Text>
);

export default Test;

Calling <Test title="Sir" name="Lancelot" /> renders "Sir Lancelot" as expected, but <Test /> results in nothing, when it should output "Mr McGee".

Any help is greatly appreciated.