diff --git a/protocol/json/server_request.go b/protocol/json/server_request.go
index ab7a6bc..3817245 100644
--- a/protocol/json/server_request.go
+++ b/protocol/json/server_request.go
@@ -130,13 +130,15 @@ func (src *ServerRequestCodec) NewResponse(reply interface{}, err error) ([]byte
 func (src *ServerRequestCodec) NewResponseWithString(reply string, err error) ([]byte, error) {
 	res := src.newServerResponse(nil, err)
 
-	var i interface{}
-	mErr := json.Unmarshal([]byte(reply), &i)
-	if nil != mErr {
-		return nil, mErr
-	}
+	if "" != reply {
+		var i interface{}
+		mErr := json.Unmarshal([]byte(reply), &i)
+		if nil != mErr {
+			return nil, mErr
+		}
 
-	res.Result = i
+		res.Result = i
+	}
 	return json.Marshal(res)
 }