diff --git a/lib/core/src/server/config/webpack.config.dev.js b/lib/core/src/server/config/webpack.config.dev.js
index 0bb728d4a17f..af0d603d4f6d 100644
--- a/lib/core/src/server/config/webpack.config.dev.js
+++ b/lib/core/src/server/config/webpack.config.dev.js
@@ -94,7 +94,7 @@ export default ({ configDir, quiet, babelOptions, entries }) => {
     resolve: {
       // Since we ship with json-loader always, it's better to move extensions to here
       // from the default config.
-      extensions: ['.js', '.jsx', '.json', '.mjs'],
+      extensions: ['.mjs', '.js', '.jsx', '.json'],
       // Add support to NODE_PATH. With this we could avoid relative path imports.
       // Based on this CRA feature: https://github.com/facebookincubator/create-react-app/issues/253
       modules: ['node_modules'].concat(nodePaths),
diff --git a/lib/core/src/server/config/webpack.config.prod.js b/lib/core/src/server/config/webpack.config.prod.js
index ea0f98f76edc..d974a5868da1 100644
--- a/lib/core/src/server/config/webpack.config.prod.js
+++ b/lib/core/src/server/config/webpack.config.prod.js
@@ -80,7 +80,7 @@ export default ({ configDir, babelOptions, entries }) => {
     resolve: {
       // Since we ship with json-loader always, it's better to move extensions to here
       // from the default config.
-      extensions: ['.js', '.jsx', '.json', '.mjs'],
+      extensions: ['.mjs', '.js', '.jsx', '.json'],
       // Add support to NODE_PATH. With this we could avoid relative path imports.
       // Based on this CRA feature: https://github.com/facebookincubator/create-react-app/issues/253
       modules: ['node_modules'].concat(nodePaths),