gatsby: [1.0] Typeface produces error in production build

I’m importing a typeface package in my default layout. It works in development. In production the font also loads, but produces the following error.

bootstrap b3d99bd…:52 Uncaught TypeError: Cannot read property 'call' of undefined
    at t (bootstrap b3d99bd…:52)
    at Object../node_modules/typeface-roboto/index.css (index.css:1)
    at t (bootstrap b3d99bd…:52)
    at Object../node_modules/babel-loader/lib/index.js?{"presets":["/Users/me/project/node_modules/babel-preset-env/lib/index.js","/Users/me/project/node_modules/babel-preset-react/lib/index.js","/Users/me/project/node_modules/babel-preset-stage-1/lib/index.js","/Users/me/project/node_modules/babel-preset-es2015/lib/index.js","/Users/me/project/node_modules/babel-preset-stage-0/lib/index.js","/Users/me/project/node_modules/babel-preset-react/lib/index.js"],"env":{"development":{"plugins":["add-module-exports","flow-react-proptypes",["styled-components",{"minify":false,"displayName":true}]]},"production":{"plugins":["add-module-exports","flow-react-proptypes",["styled-components",{"ssr":true,"displayName":false}]]}},"plugins":["/Users/me/project/node_modules/gatsby/dist/utils/babel-plugin-extract-graphql.js","/Users/me/project/node_modules/babel-plugin-add-module-exports/lib/index.js","/Users/me/project/node_modules/babel-plugin-add-module-exports/lib/index.js","/Users/me/project/node_modules/babel-plugin-transform-object-assign/lib/index.js"],"cacheDirectory":true}!./src/layouts/index.js (index.js:10)
    at t (bootstrap b3d99bd…:52)
    at index.js?9a34:3
    at window.webpackJsonp (bootstrap b3d99bd…:20)
    at layout-component---index-b4f03b0….js:1

It points to this line in bootstrap

// Execute the module function
modules[moduleId].call(module.exports, module, module.exports, __webpack_require__);

And further down

exports = module.exports = require("../css-loader/lib/css-base.js")();

in index.css

I didn’t change anything to the webpack configuration regarding css. Any idea what might cause this?