diff --git a/internal/lib/internal/filepathlite/path.go b/internal/lib/internal/filepathlite/path.go
deleted file mode 100644
index 2aaed533..00000000
--- a/internal/lib/internal/filepathlite/path.go
+++ /dev/null
@@ -1,53 +0,0 @@
-/*
- * Copyright (c) 2024 The GoPlus Authors (goplus.org). All rights reserved.
- *
- * Licensed under the Apache License, Version 2.0 (the "License");
- * you may not use this file except in compliance with the License.
- * You may obtain a copy of the License at
- *
- *     http://www.apache.org/licenses/LICENSE-2.0
- *
- * Unless required by applicable law or agreed to in writing, software
- * distributed under the License is distributed on an "AS IS" BASIS,
- * WITHOUT WARRANTIES OR CONDITIONS OF ANY KIND, either express or implied.
- * See the License for the specific language governing permissions and
- * limitations under the License.
- */
-
-package filepathlite
-
-import (
-	"github.com/goplus/llgo/internal/lib/internal/stringslite"
-)
-
-// FromSlash is filepath.ToSlash.
-func FromSlash(path string) string {
-	if Separator == '/' {
-		return path
-	}
-	return replaceStringByte(path, '/', Separator)
-}
-
-func replaceStringByte(s string, old, new byte) string {
-	if stringslite.IndexByte(s, old) == -1 {
-		return s
-	}
-	n := []byte(s)
-	for i := range n {
-		if n[i] == old {
-			n[i] = new
-		}
-	}
-	return string(n)
-}
-
-// VolumeName is filepath.VolumeName.
-func VolumeName(path string) string {
-	return FromSlash(path[:volumeNameLen(path)])
-}
-
-// VolumeNameLen returns the length of the leading volume name on Windows.
-// It returns 0 elsewhere.
-func VolumeNameLen(path string) int {
-	return volumeNameLen(path)
-}
diff --git a/internal/lib/internal/filepathlite/path_unix.go b/internal/lib/internal/filepathlite/path_unix.go
deleted file mode 100644
index e2f25598..00000000
--- a/internal/lib/internal/filepathlite/path_unix.go
+++ /dev/null
@@ -1,30 +0,0 @@
-//go:build unix || (js && wasm) || wasip1
-
-/*
- * Copyright (c) 2024 The GoPlus Authors (goplus.org). All rights reserved.
- *
- * Licensed under the Apache License, Version 2.0 (the "License");
- * you may not use this file except in compliance with the License.
- * You may obtain a copy of the License at
- *
- *     http://www.apache.org/licenses/LICENSE-2.0
- *
- * Unless required by applicable law or agreed to in writing, software
- * distributed under the License is distributed on an "AS IS" BASIS,
- * WITHOUT WARRANTIES OR CONDITIONS OF ANY KIND, either express or implied.
- * See the License for the specific language governing permissions and
- * limitations under the License.
- */
-
-package filepathlite
-
-const (
-	Separator     = '/' // OS-specific path separator
-	ListSeparator = ':' // OS-specific path list separator
-)
-
-// volumeNameLen returns length of the leading volume name on Windows.
-// It returns 0 elsewhere.
-func volumeNameLen(path string) int {
-	return 0
-}
diff --git a/internal/lib/internal/stringslite/strings.go b/internal/lib/internal/stringslite/strings.go
deleted file mode 100644
index 4ad916cc..00000000
--- a/internal/lib/internal/stringslite/strings.go
+++ /dev/null
@@ -1,17 +0,0 @@
-// Copyright 2024 The Go Authors. All rights reserved.
-// Use of this source code is governed by a BSD-style
-// license that can be found in the LICENSE file.
-
-// Package stringslite implements a subset of strings,
-// only using packages that may be imported by "os".
-//
-// Tests for these functions are in the strings package.
-package stringslite
-
-import (
-	"github.com/goplus/llgo/internal/lib/internal/bytealg"
-)
-
-func IndexByte(s string, c byte) int {
-	return bytealg.IndexByteString(s, c)
-}
diff --git a/internal/lib/os/path.go b/internal/lib/os/path.go
index a0bbb720..aee2266c 100644
--- a/internal/lib/os/path.go
+++ b/internal/lib/os/path.go
@@ -2,8 +2,6 @@ package os
 
 import (
 	"syscall"
-
-	"github.com/goplus/llgo/internal/lib/internal/filepathlite"
 )
 
 // MkdirAll creates a directory named path,
@@ -24,25 +22,19 @@ func MkdirAll(path string, perm FileMode) error {
 	}
 
 	// Slow path: make sure parent exists and then call Mkdir for path.
-
-	// Extract the parent folder from path by first removing any trailing
-	// path separator and then scanning backward until finding a path
-	// separator or reaching the beginning of the string.
-	i := len(path) - 1
-	for i >= 0 && IsPathSeparator(path[i]) {
+	i := len(path)
+	for i > 0 && IsPathSeparator(path[i-1]) { // Skip trailing path separator.
 		i--
 	}
-	for i >= 0 && !IsPathSeparator(path[i]) {
-		i--
-	}
-	if i < 0 {
-		i = 0
+
+	j := i
+	for j > 0 && !IsPathSeparator(path[j-1]) { // Scan backward over element.
+		j--
 	}
 
-	// If there is a parent directory, and it is not the volume name,
-	// recurse to ensure parent directory exists.
-	if parent := path[:i]; len(parent) > len(filepathlite.VolumeName(path)) {
-		err = MkdirAll(parent, perm)
+	if j > 1 {
+		// Create parent.
+		err = MkdirAll(fixRootDirectory(path[:j-1]), perm)
 		if err != nil {
 			return err
 		}