diff --git a/src/asar_archive.js b/src/asar_archive.js
index 05060f4..40914ac 100644
--- a/src/asar_archive.js
+++ b/src/asar_archive.js
@@ -81,8 +81,8 @@ class AsarArchive {
     const node = this.getNode(filePath)
     if (!node)
       return null
-    if (node.files)
-      return null
+    if (node.files)  // dir
+      return { path: filePath, unpacked: node.unpacked }
     if (node.link)
       return this.getFileInfo(node.link)
     const info = { path: filePath, size: node.size }
@@ -96,6 +96,8 @@ class AsarArchive {
   readFile(info) {
     if (info.unpacked)
       throw new Error('Should not use readFile for unpacked path')
+    if (typeof info.size != 'number')
+      throw new Error('readFile only works on file')
     const buffer = Buffer.alloc(info.size)
     const fd = fs.openSync(process.execPath, 'r')
     try {
@@ -109,6 +111,8 @@ class AsarArchive {
   }
 
   copyFileOut(info) {
+    if (typeof info.size != 'number')
+      throw new Error('copyFileOut only works on file')
     if (this.tmpFiles[info.path])
       return this.tmpFiles[info.path]
     if (info.unpacked)
diff --git a/test/asar_fs_realpath_dir/dir/file b/test/asar_fs_realpath_dir/dir/file
new file mode 100644
index 0000000..e69de29
diff --git a/test/asar_fs_realpath_dir/index.js b/test/asar_fs_realpath_dir/index.js
new file mode 100644
index 0000000..9f8e63a
--- /dev/null
+++ b/test/asar_fs_realpath_dir/index.js
@@ -0,0 +1,5 @@
+const fs = require('node:fs')
+const path = require('node:path')
+
+process.stdout.write(fs.realpathSync(path.join(__dirname, 'dir')))
+process.exit(0)
diff --git a/test/main.js b/test/main.js
index 21ad1bb..25b438c 100755
--- a/test/main.js
+++ b/test/main.js
@@ -110,22 +110,29 @@ describe('node', function() {
     assert.equal(result.stdout.toString().trim(), p)
   })
 
-  it('start with asar with async fs', async () => {
+  it('start with asar with offset', async () => {
+    const result = await packageAndRun('fs_async', changeOffset)
+    assert.equal(result.status, 0)
+    assert.ok(result.stdout.toString().includes('fs.readFile(__filename'))
+  })
+
+  it('async fs works on asar', async () => {
     const result = await packageAndRun('fs_async')
     assert.equal(result.status, 0)
     assert.ok(result.stdout.toString().includes('fs.readFile(__filename'))
   })
 
-  it('start with asar with promise fs', async () => {
+  it('promise fs works on asar', async () => {
     const result = await packageAndRun('fs_promise')
     assert.equal(result.status, 0)
     assert.ok(result.stdout.toString().includes('fs.readFile(__filename'))
   })
 
-  it('start with asar with offset', async () => {
-    const result = await packageAndRun('fs_async', changeOffset)
+  it('fs.realpathSync works on dir in asar', async () => {
+    const result = await packageAndRun('fs_realpath_dir')
+    console.log(result.stderr.toString())
     assert.equal(result.status, 0)
-    assert.ok(result.stdout.toString().includes('fs.readFile(__filename'))
+    assert.ok(result.stdout.toString().endsWith(path.join('asar', 'dir')));
   })
 
   it('Promise can resolve', async () => {