diff --git a/client/error.go b/client/error.go
index ec9ad8e..01eb38c 100644
--- a/client/error.go
+++ b/client/error.go
@@ -16,5 +16,8 @@ type Error struct {
 }
 
 func (e *Error) Error() string {
+	if nil == e.Err {
+		return ""
+	}
 	return e.Err.Error()
 }
diff --git a/client/request-state.go b/client/request-state.go
index fe4b034..2e89d8c 100644
--- a/client/request-state.go
+++ b/client/request-state.go
@@ -39,6 +39,9 @@ func (rs *requestState) isCanceled() bool {
 }
 
 func (rs *requestState) setError(err error) {
+	if nil == err {
+		return
+	}
 	rs.clientError = newError(rs.method, rs.params, err)
 }
 
diff --git a/protocol/json/client_response.go b/protocol/json/client_response.go
index 2d419ea..611c917 100644
--- a/protocol/json/client_response.go
+++ b/protocol/json/client_response.go
@@ -29,7 +29,7 @@ func (crc *ClientResponseCodec) ID() interface{} {
 
 func (crc *ClientResponseCodec) Result(result interface{}) error {
 	if nil == crc.res.Error && nil != crc.res.Result {
-		if err := json.Unmarshal(*crc.res.Result, result); nil != err {
+		if err := json.Unmarshal(*crc.res.Result, &result); nil != err {
 			return err
 		}
 		return nil