diff --git a/js/package.json b/js/package.json
index b64f4e6..b38dade 100644
--- a/js/package.json
+++ b/js/package.json
@@ -7,7 +7,7 @@
     "solc": "^0.8.28"
   },
   "scripts": {
-    "build": "cp ../target/wasm32-unknown-emscripten/release/resolc.js ../target/wasm32-unknown-emscripten/release/resolc.wasm ./src && npx rollup -c",
+    "build": "mkdir -p src && cp ../target/wasm32-unknown-emscripten/release/resolc.js ../target/wasm32-unknown-emscripten/release/resolc.wasm ./src && npx rollup -c",
     "test": "npm run build && node run_revive.js"
   },
   "devDependencies": {