diff --git a/src/karma-webpack.js b/src/karma-webpack.js
index 33bc1e2..3192895 100644
--- a/src/karma-webpack.js
+++ b/src/karma-webpack.js
@@ -2,7 +2,8 @@
   no-param-reassign,
   no-console,
   no-shadow,
-  func-names
+  func-names,
+  import/no-dynamic-require
 */
 
 const os = require('os');
@@ -12,7 +13,12 @@ const cloneDeep = require('clone-deep');
 const async = require('neo-async');
 const webpack = require('webpack');
 const WebpackDevMiddleware = require('webpack-dev-middleware');
-const SingleEntryDependency = require('webpack/lib/dependencies/SingleEntryDependency');
+
+const isWebpack4 = webpack.version[0] === '4';
+const dependencyPath = isWebpack4 ?
+  'webpack/lib/dependencies/SingleEntryDependency':
+  'webpack/lib/dependencies/EntryDependency';
+const SingleEntryDependency = require(dependencyPath);
 
 let blocked = [];
 let isBlocked = false;
@@ -300,11 +306,12 @@ Plugin.prototype.make = function(compilation, callback) {
 
       compilation.addEntry('', dep, name, (err) => {
         // If the module fails because of an File not found error, remove the test file
+        const module = isWebpack4 ? dep.module : compilation.moduleGraph.getModule(dep);
         if (
-          dep.module &&
-          dep.module.error &&
-          dep.module.error.error &&
-          dep.module.error.error.code === 'ENOENT'
+          module &&
+          module.error &&
+          module.error.error &&
+          module.error.error.code === 'ENOENT'
         ) {
           this.files = this.files.filter((f) => file !== f);
           invalidate(this.middleware);