diff --git a/example/readline-demo/readline-demo.go b/example/readline-demo/readline-demo.go
index 2b1daf7..8b6f69f 100644
--- a/example/readline-demo/readline-demo.go
+++ b/example/readline-demo/readline-demo.go
@@ -72,7 +72,7 @@ func filterInput(r rune) (rune, bool) {
 
 func main() {
 	l, err := readline.NewEx(&readline.Config{
-		Prompt:          "\033[31m»\033[0m ",
+		Prompt:          readline.StaticPrompt("\033[31m»\033[0m "),
 		HistoryFile:     "/tmp/readline.tmp",
 		AutoComplete:    completer,
 		InterruptPrompt: "^C",
@@ -88,7 +88,7 @@ func main() {
 
 	setPasswordCfg := l.GenPasswordConfig()
 	setPasswordCfg.SetListener(func(line []rune, pos int, key rune) (newLine []rune, newPos int, ok bool) {
-		l.SetPrompt(fmt.Sprintf("Enter password(%v): ", len(line)))
+		l.SetPrompt(readline.StaticPrompt(fmt.Sprintf("Enter password(%v): ", len(line))))
 		l.Refresh()
 		return nil, 0, false
 	})
@@ -124,7 +124,7 @@ func main() {
 				println("current mode: emacs")
 			}
 		case line == "login":
-			pswd, err := l.ReadPassword("please enter your password: ")
+			pswd, err := l.ReadPassword(readline.StaticPrompt("please enter your password: "))
 			if err != nil {
 				break
 			}
@@ -141,7 +141,7 @@ func main() {
 				log.Println("setprompt <prompt>")
 				break
 			}
-			l.SetPrompt(line[10:])
+			l.SetPrompt(readline.StaticPrompt(line[10:]))
 		case strings.HasPrefix(line, "say"):
 			line := strings.TrimSpace(line[3:])
 			if len(line) == 0 {
diff --git a/example/readline-im/readline-im.go b/example/readline-im/readline-im.go
index 16803bd..b62d864 100644
--- a/example/readline-im/readline-im.go
+++ b/example/readline-im/readline-im.go
@@ -18,7 +18,7 @@ func main() {
 	}
 	defer rl.Close()
 
-	rl.SetPrompt("username: ")
+	rl.SetPrompt(readline.StaticPrompt("username: "))
 	username, err := rl.Readline()
 	if err != nil {
 		return
@@ -27,7 +27,7 @@ func main() {
 	log.SetOutput(rl.Stderr())
 
 	fmt.Fprintln(rl, "Hi,", username+"! My name is Dave.")
-	rl.SetPrompt(username + "> ")
+	rl.SetPrompt(readline.StaticPrompt(username + "> "))
 
 	done := make(chan struct{})
 	go func() {
diff --git a/example/readline-multiline/readline-multiline.go b/example/readline-multiline/readline-multiline.go
index 2192cf6..f47d032 100644
--- a/example/readline-multiline/readline-multiline.go
+++ b/example/readline-multiline/readline-multiline.go
@@ -8,7 +8,7 @@ import (
 
 func main() {
 	rl, err := readline.NewEx(&readline.Config{
-		Prompt:                 "> ",
+		Prompt:                 readline.StaticPrompt("> "),
 		HistoryFile:            "/tmp/readline-multiline",
 		DisableAutoSaveHistory: true,
 	})
@@ -29,12 +29,12 @@ func main() {
 		}
 		cmds = append(cmds, line)
 		if !strings.HasSuffix(line, ";") {
-			rl.SetPrompt(">>> ")
+			rl.SetPrompt(readline.StaticPrompt(">>> "))
 			continue
 		}
 		cmd := strings.Join(cmds, " ")
 		cmds = cmds[:0]
-		rl.SetPrompt("> ")
+		rl.SetPrompt(readline.StaticPrompt("> "))
 		rl.SaveHistory(cmd)
 		println(cmd)
 	}
diff --git a/example/readline-pass-strength/readline-pass-strength.go b/example/readline-pass-strength/readline-pass-strength.go
index afcef45..24e8cf7 100644
--- a/example/readline-pass-strength/readline-pass-strength.go
+++ b/example/readline-pass-strength/readline-pass-strength.go
@@ -80,7 +80,7 @@ func createStrengthPrompt(password []rune) string {
 }
 
 func main() {
-	rl, err := readline.New("")
+	rl, err := readline.New(readline.StaticPrompt(""))
 	if err != nil {
 		return
 	}
@@ -88,7 +88,7 @@ func main() {
 
 	setPasswordCfg := rl.GenPasswordConfig()
 	setPasswordCfg.SetListener(func(line []rune, pos int, key rune) (newLine []rune, newPos int, ok bool) {
-		rl.SetPrompt(createStrengthPrompt(line))
+		rl.SetPrompt(readline.StaticPrompt(createStrengthPrompt(line)))
 		rl.Refresh()
 		return nil, 0, false
 	})
diff --git a/example/readline-remote/readline-remote-server/server.go b/example/readline-remote/readline-remote-server/server.go
index 38abc7d..a8f7a2a 100644
--- a/example/readline-remote/readline-remote-server/server.go
+++ b/example/readline-remote/readline-remote-server/server.go
@@ -8,7 +8,7 @@ import (
 
 func main() {
 	cfg := &readline.Config{
-		Prompt: "readline-remote: ",
+		Prompt: readline.StaticPrompt("readline-remote: "),
 	}
 	handleFunc := func(rl *readline.Instance) {
 		for {
diff --git a/operation.go b/operation.go
index 4c31624..94f52bf 100644
--- a/operation.go
+++ b/operation.go
@@ -2,6 +2,7 @@ package readline
 
 import (
 	"errors"
+	"fmt"
 	"io"
 	"sync"
 )
@@ -89,7 +90,7 @@ func NewOperation(t *Terminal, cfg *Config) *Operation {
 	return op
 }
 
-func (o *Operation) SetPrompt(s string) {
+func (o *Operation) SetPrompt(s fmt.Stringer) {
 	o.buf.SetPrompt(s)
 }
 
@@ -398,7 +399,7 @@ func (o *Operation) Runes() ([]rune, error) {
 	}
 }
 
-func (o *Operation) PasswordEx(prompt string, l Listener) ([]byte, error) {
+func (o *Operation) PasswordEx(prompt fmt.Stringer, l Listener) ([]byte, error) {
 	cfg := o.GenPasswordConfig()
 	cfg.Prompt = prompt
 	cfg.Listener = l
@@ -417,7 +418,7 @@ func (o *Operation) PasswordWithConfig(cfg *Config) ([]byte, error) {
 	return o.Slice()
 }
 
-func (o *Operation) Password(prompt string) ([]byte, error) {
+func (o *Operation) Password(prompt fmt.Stringer) ([]byte, error) {
 	return o.PasswordEx(prompt, nil)
 }
 
diff --git a/prompt.go b/prompt.go
new file mode 100644
index 0000000..0a19abf
--- /dev/null
+++ b/prompt.go
@@ -0,0 +1,11 @@
+package readline
+
+type StaticPrompt string
+
+func (s StaticPrompt) String() string {
+	return string(s)
+}
+
+func NewStaticPrompt(s string) StaticPrompt {
+	return StaticPrompt(s)
+}
diff --git a/readline.go b/readline.go
index 0e7aca0..0c541e1 100644
--- a/readline.go
+++ b/readline.go
@@ -1,7 +1,7 @@
 // Readline is a pure go implementation for GNU-Readline kind library.
 //
 // example:
-// 	rl, err := readline.New("> ")
+// 	rl, err := readline.New(readline.StaticPrompt("> "))
 // 	if err != nil {
 // 		panic(err)
 // 	}
@@ -17,7 +17,10 @@
 //
 package readline
 
-import "io"
+import (
+	"fmt"
+	"io"
+)
 
 type Instance struct {
 	Config    *Config
@@ -27,7 +30,7 @@ type Instance struct {
 
 type Config struct {
 	// prompt supports ANSI escape sequence, so we can color some characters even in windows
-	Prompt string
+	Prompt fmt.Stringer
 
 	// readline will persist historys to file where HistoryFile specified
 	HistoryFile string
@@ -94,6 +97,7 @@ func (c *Config) Init() error {
 	if c.inited {
 		return nil
 	}
+	c.Prompt = StaticPrompt("")
 	c.inited = true
 	if c.Stdin == nil {
 		c.Stdin = NewCancelableStdin(Stdin)
@@ -175,7 +179,11 @@ func NewEx(cfg *Config) (*Instance, error) {
 	}, nil
 }
 
-func New(prompt string) (*Instance, error) {
+type Prompter interface {
+	String() string
+}
+
+func New(prompt fmt.Stringer) (*Instance, error) {
 	return NewEx(&Config{Prompt: prompt})
 }
 
@@ -183,7 +191,7 @@ func (i *Instance) ResetHistory() {
 	i.Operation.ResetHistory()
 }
 
-func (i *Instance) SetPrompt(s string) {
+func (i *Instance) SetPrompt(s fmt.Stringer) {
 	i.Operation.SetPrompt(s)
 }
 
@@ -224,11 +232,11 @@ func (i *Instance) ReadPasswordWithConfig(cfg *Config) ([]byte, error) {
 	return i.Operation.PasswordWithConfig(cfg)
 }
 
-func (i *Instance) ReadPasswordEx(prompt string, l Listener) ([]byte, error) {
+func (i *Instance) ReadPasswordEx(prompt fmt.Stringer, l Listener) ([]byte, error) {
 	return i.Operation.PasswordEx(prompt, l)
 }
 
-func (i *Instance) ReadPassword(prompt string) ([]byte, error) {
+func (i *Instance) ReadPassword(prompt fmt.Stringer) ([]byte, error) {
 	return i.Operation.Password(prompt)
 }
 
diff --git a/readline_test.go b/readline_test.go
index 34a5a3b..e76d010 100644
--- a/readline_test.go
+++ b/readline_test.go
@@ -6,7 +6,9 @@ import (
 )
 
 func TestRace(t *testing.T) {
-	rl, err := NewEx(&Config{})
+	rl, err := NewEx(&Config{
+		Prompt: StaticPrompt(""),
+	})
 	if err != nil {
 		t.Fatal(err)
 		return
@@ -14,7 +16,7 @@ func TestRace(t *testing.T) {
 
 	go func() {
 		for range time.Tick(time.Millisecond) {
-			rl.SetPrompt("hello")
+			rl.SetPrompt(StaticPrompt("hello"))
 		}
 	}()
 
diff --git a/runebuf.go b/runebuf.go
index 81d2da5..c9c59e8 100644
--- a/runebuf.go
+++ b/runebuf.go
@@ -3,6 +3,7 @@ package readline
 import (
 	"bufio"
 	"bytes"
+	"fmt"
 	"io"
 	"strconv"
 	"strings"
@@ -17,7 +18,7 @@ type runeBufferBck struct {
 type RuneBuffer struct {
 	buf    []rune
 	idx    int
-	prompt []rune
+	prompt fmt.Stringer
 	w      io.Writer
 
 	hadClean    bool
@@ -35,7 +36,7 @@ type RuneBuffer struct {
 	sync.Mutex
 }
 
-func (r* RuneBuffer) pushKill(text []rune) {
+func (r *RuneBuffer) pushKill(text []rune) {
 	r.lastKill = append([]rune{}, text...)
 }
 
@@ -61,7 +62,7 @@ func (r *RuneBuffer) Restore() {
 	})
 }
 
-func NewRuneBuffer(w io.Writer, prompt string, cfg *Config, width int) *RuneBuffer {
+func NewRuneBuffer(w io.Writer, prompt fmt.Stringer, cfg *Config, width int) *RuneBuffer {
 	rb := &RuneBuffer{
 		w:           w,
 		interactive: cfg.useInteractive(),
@@ -99,7 +100,7 @@ func (r *RuneBuffer) PromptLen() int {
 }
 
 func (r *RuneBuffer) promptLen() int {
-	return runes.WidthAll(runes.ColorFilter(r.prompt))
+	return runes.WidthAll(runes.ColorFilter([]rune(r.prompt.String())))
 }
 
 func (r *RuneBuffer) RuneSlice(i int) []rune {
@@ -221,7 +222,7 @@ func (r *RuneBuffer) DeleteWord() {
 	}
 	for i := init + 1; i < len(r.buf); i++ {
 		if !IsWordBreak(r.buf[i]) && IsWordBreak(r.buf[i-1]) {
-			r.pushKill(r.buf[r.idx:i-1])
+			r.pushKill(r.buf[r.idx : i-1])
 			r.Refresh(func() {
 				r.buf = append(r.buf[:r.idx], r.buf[i-1:]...)
 			})
@@ -350,7 +351,7 @@ func (r *RuneBuffer) Yank() {
 		return
 	}
 	r.Refresh(func() {
-		buf := make([]rune, 0, len(r.buf) + len(r.lastKill))
+		buf := make([]rune, 0, len(r.buf)+len(r.lastKill))
 		buf = append(buf, r.buf[:r.idx]...)
 		buf = append(buf, r.lastKill...)
 		buf = append(buf, r.buf[r.idx:]...)
@@ -478,7 +479,7 @@ func (r *RuneBuffer) print() {
 
 func (r *RuneBuffer) output() []byte {
 	buf := bytes.NewBuffer(nil)
-	buf.WriteString(string(r.prompt))
+	buf.WriteString(r.prompt.String())
 	if r.cfg.EnableMask && len(r.buf) > 0 {
 		buf.Write([]byte(strings.Repeat(string(r.cfg.MaskRune), len(r.buf)-1)))
 		if r.buf[len(r.buf)-1] == '\n' {
@@ -582,9 +583,9 @@ func (r *RuneBuffer) Set(buf []rune) {
 	r.SetWithIdx(len(buf), buf)
 }
 
-func (r *RuneBuffer) SetPrompt(prompt string) {
+func (r *RuneBuffer) SetPrompt(prompt fmt.Stringer) {
 	r.Lock()
-	r.prompt = []rune(prompt)
+	r.prompt = prompt //[]rune(prompt)
 	r.Unlock()
 }
 
diff --git a/std.go b/std.go
index 61d44b7..63ca847 100644
--- a/std.go
+++ b/std.go
@@ -1,6 +1,7 @@
 package readline
 
 import (
+	"fmt"
 	"io"
 	"os"
 	"sync"
@@ -54,13 +55,13 @@ func AddHistory(content string) error {
 	return ins.SaveHistory(content)
 }
 
-func Password(prompt string) ([]byte, error) {
+func Password(prompt fmt.Stringer) ([]byte, error) {
 	ins := getInstance()
 	return ins.ReadPassword(prompt)
 }
 
 // readline with global configs
-func Line(prompt string) (string, error) {
+func Line(prompt fmt.Stringer) (string, error) {
 	ins := getInstance()
 	ins.SetPrompt(prompt)
 	return ins.Readline()