diff --git a/wasm/demo/package.json b/wasm/demo/package.json
index da59ab08a..b05fe5c8a 100644
--- a/wasm/demo/package.json
+++ b/wasm/demo/package.json
@@ -10,6 +10,7 @@
     },
     "devDependencies": {
         "@wasm-tool/wasm-pack-plugin": "^1.1.0",
+        "clean-webpack-plugin": "^3.0.0",
         "css-loader": "^3.4.1",
         "html-webpack-plugin": "^3.2.0",
         "mini-css-extract-plugin": "^0.9.0",
diff --git a/wasm/demo/webpack.config.js b/wasm/demo/webpack.config.js
index 7ca0910c2..67e2428f6 100644
--- a/wasm/demo/webpack.config.js
+++ b/wasm/demo/webpack.config.js
@@ -1,6 +1,8 @@
 const HtmlWebpackPlugin = require('html-webpack-plugin');
 const MiniCssExtractPlugin = require('mini-css-extract-plugin');
 const WasmPackPlugin = require('@wasm-tool/wasm-pack-plugin');
+const { CleanWebpackPlugin } = require('clean-webpack-plugin');
+
 const path = require('path');
 const fs = require('fs');
 
@@ -31,6 +33,7 @@ module.exports = (env = {}) => {
             ]
         },
         plugins: [
+            new CleanWebpackPlugin(),
             new HtmlWebpackPlugin({
                 filename: 'index.html',
                 template: 'src/index.ejs',