diff --git a/internal/lib/_errors/errors.go b/internal/lib/_errors/errors.go
deleted file mode 100644
index 5f95bdef..00000000
--- a/internal/lib/_errors/errors.go
+++ /dev/null
@@ -1,68 +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 errors
-
-// llgo:skipall
-import (
-	_ "unsafe"
-)
-
-// Unwrap returns the result of calling the Unwrap method on err, if err's
-// type contains an Unwrap method returning error.
-// Otherwise, Unwrap returns nil.
-//
-// Unwrap only calls a method of the form "Unwrap() error".
-// In particular Unwrap does not unwrap errors returned by [Join].
-func Unwrap(err error) error {
-	u, ok := err.(interface {
-		Unwrap() error
-	})
-	if !ok {
-		return nil
-	}
-	return u.Unwrap()
-}
-
-// New returns an error that formats as the given text.
-// Each call to New returns a distinct error value even if the text is identical.
-func New(text string) error {
-	return &errorString{text}
-}
-
-// errorString is a trivial implementation of error.
-type errorString struct {
-	s string
-}
-
-func (e *errorString) Error() string {
-	return e.s
-}
-
-// ErrUnsupported indicates that a requested operation cannot be performed,
-// because it is unsupported. For example, a call to [os.Link] when using a
-// file system that does not support hard links.
-//
-// Functions and methods should not return this error but should instead
-// return an error including appropriate context that satisfies
-//
-//	errors.Is(err, errors.ErrUnsupported)
-//
-// either by directly wrapping ErrUnsupported or by implementing an Is method.
-//
-// Functions and methods should document the cases in which an error
-// wrapping this will be returned.
-var ErrUnsupported = New("unsupported operation")
diff --git a/internal/lib/syscall/syscall_unix.go b/internal/lib/syscall/syscall_unix.go
index 30d66e4f..73755270 100644
--- a/internal/lib/syscall/syscall_unix.go
+++ b/internal/lib/syscall/syscall_unix.go
@@ -7,7 +7,6 @@
 package syscall
 
 import (
-	"errors"
 	"unsafe"
 
 	"github.com/goplus/llgo/c"
@@ -35,8 +34,9 @@ func (e Errno) Is(target error) bool {
 		return e == EEXIST || e == ENOTEMPTY
 	case oserror.ErrNotExist:
 		return e == ENOENT
-	case errors.ErrUnsupported:
-		return e == ENOSYS || e == ENOTSUP || e == EOPNOTSUPP
+		// TODO(xsw): go1.21
+		// case errors.ErrUnsupported:
+		//	return e == ENOSYS || e == ENOTSUP || e == EOPNOTSUPP
 	}
 	return false
 }