diff --git a/CHANGELOG.md b/CHANGELOG.md
index 28b16acc0c..2d25f66104 100644
--- a/CHANGELOG.md
+++ b/CHANGELOG.md
@@ -13,6 +13,7 @@ and this project adheres to [Semantic Versioning](https://semver.org/spec/v2.0.0
 
 ### Changed / Improved
 - Set cache tag when loading a category - @haelbichalex (#3940)
+- In development build `webpack.config.js` in theme folder is now called without the `default` key
 
 ### Fixed
 - Added Finnish translations - @mattiteraslahti and @alphpkeemik
diff --git a/core/build/dev-server.js b/core/build/dev-server.js
index 958c1b6dbf..b40d7554ff 100644
--- a/core/build/dev-server.js
+++ b/core/build/dev-server.js
@@ -2,14 +2,14 @@ const path = require('path')
 const webpack = require('webpack')
 const MFS = require('memory-fs')
 
-let baseClientConfig = require('./webpack.client.config')
-let baseServerConfig = require('./webpack.server.config')
+let baseClientConfig = require('./webpack.client.config').default
+let baseServerConfig = require('./webpack.server.config').default
 
 const themeRoot = require('./theme-path')
 const extendedConfig = require(path.join(themeRoot, '/webpack.config.js'))
 
-let clientConfig = extendedConfig(baseClientConfig, { isClient: true, isDev: true }).default;
-let serverConfig = extendedConfig(baseServerConfig, { isClient: false, isDev: true }).default;
+let clientConfig = extendedConfig(baseClientConfig, { isClient: true, isDev: true })
+let serverConfig = extendedConfig(baseServerConfig, { isClient: false, isDev: true })
 
 module.exports = function setupDevServer (app, cb) {
   let bundle