diff --git a/src/config.ts b/src/config.ts
index fe04c84..c874bc9 100644
--- a/src/config.ts
+++ b/src/config.ts
@@ -20,7 +20,7 @@ import assetPlugin from './plugins/asset'
 import workerPlugin from './plugins/worker'
 import importMetaUrlPlugin from './plugins/importMetaUrl'
 import esmShimPlugin from './plugins/esm'
-import { isObject } from './utils'
+import { isObject, isFilePathESM } from './utils'
 
 export { defineConfig as defineViteConfig } from 'vite'
 
@@ -240,11 +240,7 @@ export async function loadConfigFromFile(
     }
   }
 
-  // electron does not support adding type: "module" to package.json
-  let isESM = false
-  if (/\.m[jt]s$/.test(resolvedPath) || resolvedPath.endsWith('.ts')) {
-    isESM = true
-  }
+  const isESM = isFilePathESM(resolvedPath)
 
   try {
     const bundled = await bundleConfigFile(resolvedPath, isESM)
diff --git a/src/utils.ts b/src/utils.ts
index e53be1a..6ba3f7b 100644
--- a/src/utils.ts
+++ b/src/utils.ts
@@ -73,3 +73,14 @@ export function loadPackageData(root = process.cwd()): PackageData | null {
   }
   return null
 }
+
+export function isFilePathESM(filePath: string): boolean {
+  if (/\.m[jt]s$/.test(filePath) || filePath.endsWith('.ts')) {
+    return true
+  } else if (/\.c[jt]s$/.test(filePath)) {
+    return false
+  } else {
+    const pkg = loadPackageData()
+    return pkg?.type === 'module'
+  }
+}