diff --git a/client/operation.go b/client/operation.go
index 6e66cd6..676aaee 100644
--- a/client/operation.go
+++ b/client/operation.go
@@ -413,7 +413,7 @@ func (hc *houstonClient) launch(meta *procmeta) error {
 	go stdReader(meta.name, stdout, index)
 
 	logger.Println("startChildProcess :", meta.cmd.Args)
-	meta.cmd.Env = append(meta.cmd.Env, fmt.Sprintf("HOUSTON_SIBLIING_INDEX=%d", index))
+	meta.cmd.Env = append(os.Environ(), fmt.Sprintf("HOUSTON_SIBLIING_INDEX=%d", index))
 	err = meta.cmd.Start()
 	if err == nil {
 		logger.Println("process index, pid =", index, meta.cmd.Process.Pid)
@@ -424,8 +424,6 @@ func (hc *houstonClient) launch(meta *procmeta) error {
 	return err
 }
 
-var errPrepareprocessLaunchFailed = errors.New("prepareProcessLaunch failed")
-
 func (hc *houstonClient) startChildProcess(req *shared.StartProcessRequest, op protos.OperationClient) error {
 	meta, err := prepareProcessLaunch(hc.config.StorageRoot, req)
 	if err != nil {