use cross-env

package.json

@@ -5,10 +5,10 @@
   "private": true,
   "scripts": {
     "dev": "node server",
-    "start": "NODE_ENV=production node server",
+    "start": "cross-env NODE_ENV=production node server",
     "build": "npm run build:client && npm run build:server",
-    "build:client": "NODE_ENV=production webpack --config build/webpack.client.config.js --progress --hide-modules",
-    "build:server": "NODE_ENV=production webpack --config build/webpack.server.config.js --progress --hide-modules"
+    "build:client": "cross-env NODE_ENV=production webpack --config build/webpack.client.config.js --progress --hide-modules",
+    "build:server": "cross-env NODE_ENV=production webpack --config build/webpack.server.config.js --progress --hide-modules"
   },
   "dependencies": {
     "es6-promise": "^3.2.1",
@@ -29,6 +29,7 @@
     "babel-loader": "^6.0.0",
     "babel-preset-es2015": "^6.13.2",
     "babel-preset-stage-2": "^6.11.0",
+    "cross-env": "^2.0.0",
     "css-loader": "^0.23.1",
     "extract-text-webpack-plugin": "^2.0.0-beta.3",
     "file-loader": "^0.8.4",