postcss TypeError: require is not a function

/* 
    This type of setup worked for me, require calls modified
	to suit my setup.
	You will have to enter the postcss-* pkgs listed in your
	package.json
*/

module.exports = (ctx) => {
  return {
    map: ctx.env === 'development' ? 'inline' : false,
    plugins: [
        require('postcss-csso')()
    ]
  } 
}