diff --git a/proxy/stratum.go b/proxy/stratum.go
index 53139c9..bf2013c 100644
--- a/proxy/stratum.go
+++ b/proxy/stratum.go
@@ -5,6 +5,7 @@ import (
 	"crypto/tls"
 	"encoding/json"
 	"errors"
+	"fmt"
 	"io"
 	"log"
 	"math/rand"
@@ -245,7 +246,7 @@ func (cs *Session) handleTCPMessage(s *ProxyServer, req *StratumReq) error {
 			_, errReply := s.handleLoginRPC(cs, params, req.Worker)
 			if errReply != nil {
 				return cs.sendStratumError(req.Id, []string{
-					string(errReply.Code),
+					fmt.Sprint(errReply.Code),
 					errReply.Message,
 				})
 			}
@@ -331,7 +332,7 @@ func (cs *Session) handleTCPMessage(s *ProxyServer, req *StratumReq) error {
 			reply, errReply := s.handleLoginRPC(cs, params, req.Worker)
 			if errReply != nil {
 				return cs.sendStratumError(req.Id, []string{
-					string(errReply.Code),
+					fmt.Sprint(errReply.Code),
 					errReply.Message,
 				})
 			}
@@ -646,7 +647,7 @@ func (cs *Session) sendJob(s *ProxyServer, id json.RawMessage, newjob bool) erro
 		reply, errReply := s.handleGetWorkRPC(cs)
 		if errReply != nil {
 			return cs.sendStratumError(id, []string{
-				string(errReply.Code),
+				fmt.Sprint(errReply.Code),
 				errReply.Message,
 			})
 		}