diff --git a/karma.conf.js b/karma.conf.js
index 996a5adf4..a61407dc1 100644
--- a/karma.conf.js
+++ b/karma.conf.js
@@ -55,6 +55,7 @@ module.exports = function(config) {
     },
 
     webpack: {
+      mode: 'development',
       devtool: 'inline-source-map',
       node: {
         Buffer: false,
diff --git a/package.json b/package.json
index 20834a86e..d40f0bba1 100644
--- a/package.json
+++ b/package.json
@@ -39,7 +39,8 @@
     "nodejs-websocket": "^1.7.1",
     "nyc": "^15.0.0",
     "opts": "^1.2.7",
-    "webpack": "^3.11.0",
+    "webpack": "^4.41.6",
+    "webpack-cli": "^3.3.11",
     "worker-loader": "^2.0.0"
   },
   "repository": {
diff --git a/webpack.config.js b/webpack.config.js
index 806401eff..df0db4d34 100644
--- a/webpack.config.js
+++ b/webpack.config.js
@@ -6,7 +6,6 @@
  * Copyright 2011-2016 Digital Bazaar, Inc.
  */
 const path = require('path');
-const webpack = require('webpack');
 
 // build multiple outputs
 module.exports = [];
@@ -79,6 +78,7 @@ outputs.forEach(info => {
 
   // plain unoptimized unminified bundle
   const bundle = Object.assign({}, common, {
+    mode: 'development',
     output: {
       path: path.join(__dirname, 'dist'),
       filename: info.filenameBase + '.js',
@@ -95,6 +95,7 @@ outputs.forEach(info => {
 
   // optimized and minified bundle
   const minify = Object.assign({}, common, {
+    mode: 'production',
     output: {
       path: path.join(__dirname, 'dist'),
       filename: info.filenameBase + '.min.js',
@@ -103,6 +104,7 @@ outputs.forEach(info => {
     },
     devtool: 'cheap-module-source-map',
     plugins: [
+      /*
       new webpack.optimize.UglifyJsPlugin({
         sourceMap: true,
         compress: {
@@ -113,6 +115,7 @@ outputs.forEach(info => {
         }
         //beautify: true
       })
+      */
     ]
   });
   if(info.library === null) {