diff --git a/mmdebstrap b/mmdebstrap
index f997ac4..b4d2fd6 100755
--- a/mmdebstrap
+++ b/mmdebstrap
@@ -4150,7 +4150,7 @@ sub main() {
     # this is like:
     # lxc-usernsexec -- lxc-unshare -s 'MOUNT|PID|UTSNAME|IPC' ...
     # but without needing lxc
-    if ($ARGV[0] eq "--unshare-helper") {
+    if (scalar @ARGV >= 1 && $ARGV[0] eq "--unshare-helper") {
         if ($EFFECTIVE_USER_ID != 0 && !test_unshare_userns(1)) {
             exit 1;
         }