### OS? > Windows 7, 8 or 10. Linux (which distribution). ### Versions. > angular-cli: 1.0.0-beta.21 node: 6.9.1 os: win32 x64 Run `ng build`, autoprefixer works fine. Run `ng build --prod`, autoprefixer not work. Change file `angular-cli\models\webpack-build-production.ts`, add `autoprefixer()` to `LoaderOptionsPlugin`, then `ng build --prod` works fine.