diff --git a/tools/build.js b/tools/build.js
index e7d7121..65e04a8 100644
--- a/tools/build.js
+++ b/tools/build.js
@@ -28,7 +28,7 @@ exec('babel modules -d es --ignore __tests__', {
 console.log('\nBuilding react-media.js ...')
 
 exec('webpack modules/index.js umd/react-media.js', {
-  NODE_ENV: 'production'
+  NODE_ENV: 'development'
 })
 
 console.log('\nBuilding react-media.min.js ...')