diff --git a/um_wasm_loader/build.js b/um_wasm_loader/build.js
index 62e6e4d..d689266 100644
--- a/um_wasm_loader/build.js
+++ b/um_wasm_loader/build.js
@@ -92,9 +92,6 @@ async function main() {
   // Ask rollup to build bundles.
   await run(['pnpm', 'build:bundle']);
   await run(['pnpm', 'exec', 'prettier', '--ignore-path', '', '-w', 'dist/loader.d.ts']);
-  await replaceFileByRegex(path.join(wasmDistDir, 'loader.mjs'), [
-    ['fetch(filepath)', 'fetch(new URL(filepath, import.meta.url))'],
-  ]);
 }
 
 main()
diff --git a/um_wasm_loader/src/loader.mjs b/um_wasm_loader/src/loader.mjs
index 6d8c15b..d4f6de3 100644
--- a/um_wasm_loader/src/loader.mjs
+++ b/um_wasm_loader/src/loader.mjs
@@ -8,14 +8,15 @@ function loader() {
     initSync({ module: umWasm() });
     return Promise.resolve(true);
   } else {
-    /** @type {Promise<Buffer>|undefined} */
-    let wasm = undefined;
-    if (typeof document === 'undefined') {
-      // node
-      wasm = import('node:f' + 's/promises').then((fs) =>
-        fs.readFile(new URL('../pkg/um_wasm_bg.wasm', import.meta.url)),
-      );
-    }
+    const url = new URL('um_wasm_bg.wasm', import.meta.url);
+    const wasm =
+      url.protocol === 'file:'
+        ? import('node:f' + 's/promises')
+            .then((fs) => fs.readFile(url))
+            .catch((err) => {
+              console.log('read wasm failed', err);
+            })
+        : undefined;
     return __wbg_init({ module_or_path: wasm }).then(() => true);
   }
 }