diff --git a/package.json b/package.json
index b39779db..d052e05d 100644
--- a/package.json
+++ b/package.json
@@ -35,7 +35,7 @@
     "babel-preset-es2015": "^6.24.1",
     "buffer-loader": "0.0.1",
     "canvas-toBlob": "1.0.0",
-    "copy-webpack-plugin": "4.2.1",
+    "copy-webpack-plugin": "^4.5.1",
     "decode-html": "2.0.0",
     "escape-html": "1.0.3",
     "eslint": "^4.5.0",
@@ -67,8 +67,9 @@
     "tap": "^11.0.1",
     "text-encoding": "0.6.4",
     "tiny-worker": "^2.1.1",
-    "webpack": "^3.10.0",
-    "webpack-dev-server": "^2.4.1",
-    "worker-loader": "1.1.0"
+    "webpack": "4",
+    "webpack-cli": "^2.0.15",
+    "webpack-dev-server": "^3.1.3",
+    "worker-loader": "^1.1.1"
   }
 }
diff --git a/webpack.config.js b/webpack.config.js
index ad40a58b..ec539c49 100644
--- a/webpack.config.js
+++ b/webpack.config.js
@@ -1,9 +1,10 @@
 const CopyWebpackPlugin = require('copy-webpack-plugin');
 const defaultsDeep = require('lodash.defaultsdeep');
 const path = require('path');
-const webpack = require('webpack');
+const UglifyJsPlugin = require('uglifyjs-webpack-plugin');
 
 const base = {
+    mode: process.env.NODE_ENV === 'production' ? 'production' : 'development',
     devServer: {
         contentBase: false,
         host: '0.0.0.0',
@@ -28,12 +29,14 @@ const base = {
             loader: 'file-loader'
         }]
     },
-    plugins: process.env.NODE_ENV === 'production' ? [
-        new webpack.optimize.UglifyJsPlugin({
-            include: /\.min\.js$/,
-            minimize: true
-        })
-    ] : []
+    optimization: {
+        minimizer: [
+            new UglifyJsPlugin({
+                include: /\.min\.js$/
+            })
+        ]
+    },
+    plugins: []
 };
 
 module.exports = [
@@ -129,6 +132,9 @@ module.exports = [
                 }
             ])
         },
+        performance: {
+            hints: false
+        },
         plugins: base.plugins.concat([
             new CopyWebpackPlugin([{
                 from: 'node_modules/scratch-blocks/media',