diff --git a/builder/remotecontext/git/gitutils.go b/builder/remotecontext/git/gitutils.go
index d6e3d1935535d..1037ef5821a9e 100644
--- a/builder/remotecontext/git/gitutils.go
+++ b/builder/remotecontext/git/gitutils.go
@@ -21,6 +21,7 @@ type gitRepo struct {
 	isolateConfig bool
 }
 
+// CloneOption changes the behaviour of Clone().
 type CloneOption func(*gitRepo)
 
 // WithIsolatedConfig disables reading the user or system gitconfig files when
@@ -213,7 +214,7 @@ func (repo gitRepo) gitWithinDir(dir string, args ...string) ([]byte, error) {
 	cmd := exec.Command("git", args...)
 	cmd.Dir = dir
 	// Disable unsafe remote protocols.
-	cmd.Env = append(cmd.Env, "GIT_PROTOCOL_FROM_USER=0")
+	cmd.Env = append(os.Environ(), "GIT_PROTOCOL_FROM_USER=0")
 
 	if repo.isolateConfig {
 		cmd.Env = append(cmd.Env,