diff --git a/src/index.js b/src/index.js
index 5e1dc04f..f3100db4 100644
--- a/src/index.js
+++ b/src/index.js
@@ -142,7 +142,7 @@ class MiniCssExtractPlugin {
             );
           }
 
-          module.buildInfo = module.buildInfo || { assets: {} };
+          module.buildInfo = module.buildInfo || {};
           module.buildInfo.assets = {
             ...module.buildInfo.assets,
             ...assets,
diff --git a/src/loader.js b/src/loader.js
index fa35f44a..d34adf11 100644
--- a/src/loader.js
+++ b/src/loader.js
@@ -78,7 +78,7 @@ export function pitch(request) {
   );
 
   let source;
-  let assets = {};
+  const assets = {};
   childCompiler.hooks.afterCompile.tap(pluginName, (compilation) => {
     source =
       compilation.assets[childFilename] &&
@@ -87,7 +87,7 @@ export function pitch(request) {
     // Collect assets from modules
     compilation.modules.forEach((module) => {
       if (module.buildInfo && module.buildInfo.assets) {
-        assets = { ...assets, ...module.buildInfo.assets };
+        Object.assign(assets, module.buildInfo.assets);
       }
     });