diff --git a/README.md b/README.md
index b9ac2a6..43e462e 100644
--- a/README.md
+++ b/README.md
@@ -3,6 +3,10 @@ base16384 interface of golang
 
 ## Functions
 
+### func EncodeString(b string) []byte
+Encode string b to utf16be.
+### func DecodeString(d []byte) string
+Decode to string from encoded b.
 ### func Encode(b []byte) []byte
 Encode b to utf16be.
 ### func Decode(b []byte) []byte
@@ -11,8 +15,6 @@ Decode from encoded b.
 Display the result.
 ### func UTF82utf16be(b []byte) ([]byte, error)
 Turn the result to its original coding form to decode.
-### func Free(b []byte)
-Free memory allocated by encode / decode.
 
 # Usage
 ## As package
diff --git a/base14.go b/base14.go
index cc9cca5..06e6d15 100644
--- a/base14.go
+++ b/base14.go
@@ -13,8 +13,8 @@ func EncodeString(s string) []byte {
 	return Encode(helper.StringToBytes(s))
 }
 
-func DecodeString(s string) []byte {
-	return Decode(helper.StringToBytes(s))
+func DecodeString(d []byte) string {
+	return helper.BytesToString(Decode(d))
 }
 
 func Encode(b []byte) (encd []byte) {
diff --git a/base14_test.go b/base14_test.go
index ad80ad3..df5a827 100644
--- a/base14_test.go
+++ b/base14_test.go
@@ -13,7 +13,7 @@ func TestBase14(t *testing.T) {
 		d, err := UTF82utf16be(es)
 		if string(d) == string(e) {
 			if err == nil {
-				ds := string(Decode(d))
+				ds := DecodeString(d)
 				t.Log(ds)
 				if ds != teststr {
 					t.Fail()