``` Component Hobby declared `PropTypes` instead of `propTypes`. Did you misspell the property assignment ``` ``` import React from 'react'; import PropTypes from 'prop-types'; class Hobby extends React.Component{ render(){ return <li>{this.props.hobby}</li> } } Hobby.PropTypes={ hobby:PropTypes.string.isRequired } export default Hobby; ``` ``` Hobby.PropTypes={ hobby:PropTypes.string.isRequired } ``` ``` Hobby.propTypes={ hobby:PropTypes.string.isRequired } ```