diff --git a/log.go b/log.go
index ed13b84..8037052 100644
--- a/log.go
+++ b/log.go
@@ -107,13 +107,13 @@ func (l *Logger) output(lev Llevel, depth int, fields H, v ...interface{}) {
 		Message: msg,
 		Level:   lev,
 		Time:    time.Now(),
-		Caller:  caller(depth),
+		Caller:  Caller(depth),
 		Color:   l.color,
 	}
 	switch lev {
 	case Lerror:
 		if !PROD {
-			data.Stack = stack()
+			data.Stack = Stack()
 		}
 		// disable stack trace on debug
 		// case Ldebug:
diff --git a/log_test.go b/log_test.go
index 2daaa93..95f0a8e 100644
--- a/log_test.go
+++ b/log_test.go
@@ -210,7 +210,7 @@ func BenchmarkStackSTDStr(b *testing.B) {
 	l.SetErrOutput(io.Discard)
 	l.SetOutput(io.Discard)
 	for i := 0; i < b.N; i++ {
-		l.Info(stack())
+		l.Info(Stack())
 	}
 }
 
@@ -220,7 +220,7 @@ func BenchmarkStackCust(b *testing.B) {
 	l.SetErrOutput(io.Discard)
 	l.SetOutput(io.Discard)
 	for i := 0; i < b.N; i++ {
-		l.Info(Stack(3))
+		l.Info(StackSkip(3))
 	}
 }
 
@@ -230,6 +230,6 @@ func BenchmarkStackCustStr(b *testing.B) {
 	l.SetErrOutput(io.Discard)
 	l.SetOutput(io.Discard)
 	for i := 0; i < b.N; i++ {
-		l.Info(string(Stack(3)))
+		l.Info(string(StackSkip(3)))
 	}
 }
diff --git a/util.go b/util.go
index 07e28e3..457ae7f 100644
--- a/util.go
+++ b/util.go
@@ -7,7 +7,7 @@ import (
 	"runtime"
 )
 
-func caller(depth int) string {
+func Caller(depth int) string {
 	_, file, line, _ := runtime.Caller(depth)
 	short := file
 	for i := len(file) - 1; i > 0; i-- {
@@ -19,7 +19,7 @@ func caller(depth int) string {
 	return fmt.Sprintf("%s:%d", short, line)
 }
 
-func stack() string {
+func Stack() string {
 	buf := make([]byte, 1024)
 	for {
 		n := runtime.Stack(buf, false)
@@ -49,7 +49,7 @@ var (
 )
 
 // Stack returns a nicely formatted stack frame, skipping skip frames.
-func Stack(skip int) []byte {
+func StackSkip(skip int) []byte {
 	buf := new(bytes.Buffer) // the returned data
 	// As we loop, we open files and read them. These variables record the currently
 	// loaded file.