diff --git a/VERSION b/VERSION
index d4dfa56..1e66a61 100644
--- a/VERSION
+++ b/VERSION
@@ -1 +1 @@
-v0.3.0
\ No newline at end of file
+v0.3.1
\ No newline at end of file
diff --git a/file_logger.go b/file_logger.go
index 1332ce3..74664f8 100644
--- a/file_logger.go
+++ b/file_logger.go
@@ -8,10 +8,10 @@ import (
 	"path/filepath"
 	"strings"
 	"sync"
+	"sync/atomic"
 	"time"
 
 	"github.com/no-src/log/formatter"
-	"github.com/no-src/log/internal/cbool"
 	"github.com/no-src/log/level"
 	"github.com/no-src/log/option"
 )
@@ -35,7 +35,7 @@ type fileLogger struct {
 	in          chan logMsg
 	writer      *bufio.Writer
 	initialized bool
-	closed      *cbool.CBool
+	closed      atomic.Bool
 	close       chan struct{} // the log is closed, and wait to write all the logs
 	mu          sync.Mutex    // avoid data race for writer
 	date        time.Time
@@ -61,11 +61,10 @@ func NewFileLoggerWithAutoFlush(lvl level.Level, logDir string, filePrefix strin
 // NewFileLoggerWithOption get a file logger with option
 func NewFileLoggerWithOption(opt option.FileLoggerOption) (Logger, error) {
 	logger := &fileLogger{
-		opt:    opt,
-		in:     make(chan logMsg, 100),
-		close:  make(chan struct{}, 1),
-		mu:     sync.Mutex{},
-		closed: cbool.New(false),
+		opt:   opt,
+		in:    make(chan logMsg, 100),
+		close: make(chan struct{}, 1),
+		mu:    sync.Mutex{},
 	}
 	// init baseLogger
 	logger.baseLogger.init(logger, opt.Level, true)
@@ -76,7 +75,7 @@ func NewFileLoggerWithOption(opt option.FileLoggerOption) (Logger, error) {
 
 func (l *fileLogger) Close() error {
 	// stop a new log to write
-	l.closed.Set(true)
+	l.closed.Store(true)
 	// send a closed message
 	l.in <- closeLogMsg
 	// wait to receive a close finished message
@@ -203,7 +202,7 @@ func (l *fileLogger) startAutoFlush() {
 		delayCheckCount := 10
 		for {
 			<-time.After(wait)
-			if l.closed.Get() {
+			if l.closed.Load() {
 				return
 			}
 			l.mu.Lock()
@@ -233,7 +232,7 @@ func (l *fileLogger) Write(p []byte) (n int, err error) {
 	}
 	cp := make([]byte, pLen)
 	copy(cp, p)
-	if !l.closed.Get() {
+	if !l.closed.Load() {
 		l.in <- logMsg{
 			log:    cp,
 			closed: false,
diff --git a/internal/cbool/cbool.go b/internal/cbool/cbool.go
deleted file mode 100644
index 0d12c2b..0000000
--- a/internal/cbool/cbool.go
+++ /dev/null
@@ -1,35 +0,0 @@
-package cbool
-
-import (
-	"sync/atomic"
-)
-
-// CBool a concurrent safe bool
-type CBool struct {
-	v atomic.Bool
-}
-
-// New create an instance of CBool
-func New(v bool) *CBool {
-	cb := &CBool{}
-	cb.v.Store(v)
-	return cb
-}
-
-// Get return the bool value
-func (cb *CBool) Get() bool {
-	return cb.v.Load()
-}
-
-// Set to set the bool value
-func (cb *CBool) Set(v bool) {
-	cb.v.Store(v)
-}
-
-// SetC to set the bool value and return a closed channel
-func (cb *CBool) SetC(v bool) <-chan struct{} {
-	cb.Set(v)
-	c := make(chan struct{})
-	close(c)
-	return c
-}
diff --git a/internal/cbool/cbool_test.go b/internal/cbool/cbool_test.go
deleted file mode 100644
index 6cfcc92..0000000
--- a/internal/cbool/cbool_test.go
+++ /dev/null
@@ -1,67 +0,0 @@
-package cbool
-
-import (
-	"sync"
-	"testing"
-)
-
-func TestCBool(t *testing.T) {
-	expect := true
-	cb := New(expect)
-	actual := cb.Get()
-	if actual != expect {
-		t.Errorf("test CBoll New and Get failed, expect:%v, actual:%v", expect, actual)
-	}
-
-	expect = false
-	cb.Set(expect)
-	actual = cb.Get()
-	if actual != expect {
-		t.Errorf("test CBoll Set and Get failed, expect:%v, actual:%v", expect, actual)
-	}
-
-	expect = true
-	c := cb.SetC(expect)
-	actual = cb.Get()
-	if actual != expect {
-		t.Errorf("test CBoll SetC and Get failed, expect:%v, actual:%v", expect, actual)
-	}
-	_, ok := <-c
-	if ok {
-		t.Errorf("test CBoll SetC value failed, channel should be closed")
-	}
-}
-
-func TestCBool_Concurrent(t *testing.T) {
-	cb := New(false)
-	wg := sync.WaitGroup{}
-	count := 10
-	wg.Add(count * 3)
-	for i := 0; i < count; i++ {
-		go func() {
-			cb.Get()
-			wg.Done()
-		}()
-
-		go func() {
-			cb.Set(true)
-			wg.Done()
-		}()
-
-		go func() {
-			<-cb.SetC(true)
-			wg.Done()
-		}()
-	}
-	wg.Wait()
-}
-
-func BenchmarkCBool(b *testing.B) {
-	b.ReportAllocs()
-	b.ResetTimer()
-	cb := New(false)
-	for i := 0; i < b.N; i++ {
-		cb.Set(true)
-		cb.Get()
-	}
-}