diff --git a/src/lib/storage.js b/src/lib/storage.js
index 6d858e6c2..b2094c118 100644
--- a/src/lib/storage.js
+++ b/src/lib/storage.js
@@ -25,6 +25,10 @@ class Storage extends ScratchStorage {
             [this.AssetType.ImageVector, this.AssetType.ImageBitmap, this.AssetType.Sound],
             asset => `${ASSET_SERVER}/internalapi/asset/${asset.assetId}.${asset.dataFormat}/get/`
         );
+        this.addWebSource(
+            [this.AssetType.Sound],
+            asset => `/static/extension-assets/scratch3_music/${asset.assetId}.${asset.dataFormat}`
+        );
         defaultProjectAssets.forEach(asset => this.cache(
             this.AssetType[asset.assetType],
             this.DataFormat[asset.dataFormat],
diff --git a/webpack.config.js b/webpack.config.js
index e9b97f9ef..5a654cfcd 100644
--- a/webpack.config.js
+++ b/webpack.config.js
@@ -107,6 +107,10 @@ module.exports = {
             from: 'node_modules/scratch-blocks/media',
             to: 'static/blocks-media'
         }]),
+        new CopyWebpackPlugin([{
+            from: 'node_modules/scratch-vm/dist/node/assets',
+            to: 'static/extension-assets'
+        }]),
         new CopyWebpackPlugin([{
             from: 'extensions/**',
             to: 'static',