diff --git a/.gitignore b/.gitignore
index 98d9f7f..4ce65a5 100644
--- a/.gitignore
+++ b/.gitignore
@@ -1,4 +1,5 @@
 .idea
+*.map
 node_modules
 npm-debug.log
 docs
@@ -15,4 +16,4 @@ test/browser/refs
 test/node/diffs
 test/node/refs
 __snapshots__
-__compare__
\ No newline at end of file
+__compare__
diff --git a/webpack.demo.config.js b/webpack.demo.config.js
index 8d055cb..a46cb82 100644
--- a/webpack.demo.config.js
+++ b/webpack.demo.config.js
@@ -29,7 +29,7 @@ License ${pkg.license}`;
     return {
         entry: { [name]: './demo/src/index.js' },
         node: false,
-        devtool: 'source-map',
+        devtool: devServer ? 'source-map' : 'none',
         output: {
             library: 'MatterDemo',
             libraryTarget: 'umd',