diff --git a/stack.sh b/stack.sh
index 29394ab..e99d72c 100755
--- a/stack.sh
+++ b/stack.sh
@@ -44,7 +44,7 @@ if [[ $EUID -eq 0 ]]; then
    apt-get install -y sudo
    if ! getent passwd | grep -q stack; then
        echo "Creating a user called stack"
-       useradd -g sudo -s /bin/bash -m stack
+       useradd -U -G sudo -s /bin/bash -m stack
     fi
     echo "Making sure stack has passwordless sudo"
     sed -i "/^%sudo/ { / ALL/ { s/ ALL/ NOPASSWD:ALL/ }}" /etc/sudoers