diff --git a/um_wasm_loader/pnpm-lock.yaml b/um_wasm_loader/pnpm-lock.yaml
index f0f5b1c..111cd2f 100644
--- a/um_wasm_loader/pnpm-lock.yaml
+++ b/um_wasm_loader/pnpm-lock.yaml
@@ -257,11 +257,13 @@ snapshots:
     dependencies:
       '@rollup/pluginutils': 5.1.0(rollup@4.21.2)
       magic-string: 0.30.11
+    optionalDependencies:
       rollup: 4.21.2
 
   '@rollup/plugin-wasm@6.2.2(rollup@4.21.2)':
     dependencies:
       '@rollup/pluginutils': 5.1.0(rollup@4.21.2)
+    optionalDependencies:
       rollup: 4.21.2
 
   '@rollup/pluginutils@5.1.0(rollup@4.21.2)':
@@ -269,6 +271,7 @@ snapshots:
       '@types/estree': 1.0.5
       estree-walker: 2.0.2
       picomatch: 2.3.1
+    optionalDependencies:
       rollup: 4.21.2
 
   '@rollup/rollup-android-arm-eabi@4.21.2':
diff --git a/um_wasm_loader/rollup.config.mjs b/um_wasm_loader/rollup.config.mjs
index 3d0d46a..db00b8f 100644
--- a/um_wasm_loader/rollup.config.mjs
+++ b/um_wasm_loader/rollup.config.mjs
@@ -5,7 +5,12 @@ import { dts } from 'rollup-plugin-dts';
 
 function makePlugins({ sync }) {
   const plugins = [];
-  plugins.push(wasm({ sync: sync ? ['pkg/um_wasm_bg.wasm'] : [] }));
+  plugins.push(
+    wasm({
+      sync: sync ? ['pkg/um_wasm_bg.wasm'] : [],
+      fileName: 'um_wasm_bg.wasm',
+    }),
+  );
   plugins.push(
     replace({
       preventAssignment: true,
diff --git a/um_wasm_loader/src/loader.mjs b/um_wasm_loader/src/loader.mjs
index 52c204e..6d8c15b 100644
--- a/um_wasm_loader/src/loader.mjs
+++ b/um_wasm_loader/src/loader.mjs
@@ -1,15 +1,22 @@
 import umWasm from '../pkg/um_wasm_bg.wasm';
 import { __wbg_init, initSync } from '../pkg/um_wasm.js';
+
 export * from '../pkg/um_wasm.js';
 
 function loader() {
   if (process.env.UMC_INLINE_BUILD === '1') {
     initSync({ module: umWasm() });
-    return Promise.resolve(undefined);
+    return Promise.resolve(true);
   } else {
-    return umWasm().then(async (wasm) => {
-      await __wbg_init({ module_or_path: wasm });
-    });
+    /** @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)),
+      );
+    }
+    return __wbg_init({ module_or_path: wasm }).then(() => true);
   }
 }
 
diff --git a/um_wasm_loader/test.cjs b/um_wasm_loader/test.cjs
new file mode 100644
index 0000000..5e4c422
--- /dev/null
+++ b/um_wasm_loader/test.cjs
@@ -0,0 +1,8 @@
+const { NCMFile, ready } = require('./dist/loader.js');
+
+ready.then(() => {
+  const ncm = new NCMFile();
+  let n = ncm.open(new Uint8Array([]));
+  console.assert(n !== 0, 'n should not be 0', { n });
+  console.log('cjs test ok');
+});
diff --git a/um_wasm_loader/test.mjs b/um_wasm_loader/test.mjs
new file mode 100644
index 0000000..24b46f4
--- /dev/null
+++ b/um_wasm_loader/test.mjs
@@ -0,0 +1,8 @@
+import { NCMFile, ready } from './dist/loader.mjs';
+
+ready.then(() => {
+  const ncm = new NCMFile();
+  let n = ncm.open(new Uint8Array([]));
+  console.assert(n !== 0, 'n should not be 0', { n });
+  console.log('mjs test ok');
+});