diff --git a/cmdext/cmdrunner.go b/cmdext/cmdrunner.go
index 49d749e..22b3d06 100644
--- a/cmdext/cmdrunner.go
+++ b/cmdext/cmdrunner.go
@@ -16,7 +16,8 @@ type CommandResult struct {
 
 func run(opt CommandRunner) (CommandResult, error) {
 	cmd := exec.Command(opt.program, opt.args...)
-	cmd.Env = append(cmd.Env, opt.env)
+
+	cmd.Env = append(cmd.Env, opt.env...)
 
 	stdoutPipe, err := cmd.StdoutPipe()
 	if err != nil {