diff --git a/build.js b/build.js
index 09fd17c..e42bb7b 100644
--- a/build.js
+++ b/build.js
@@ -13,7 +13,7 @@ const exec = require('util').promisify(require('child_process').exec);
         public: pathJoin(__dirname, 'public'),
         debug: isDebug,
         swc: {
-            es: 'es2020',
+            es: 'es5',
         },
         vars: {
             html: {