diff --git a/ubuntu/16.04/config-user.sh b/ubuntu/16.04/config-user.sh
index 2c3d110..f0fcd09 100644
--- a/ubuntu/16.04/config-user.sh
+++ b/ubuntu/16.04/config-user.sh
@@ -7,7 +7,12 @@
 # Major thanks to: http://c-nergy.be/blog/?p=10752 for the tips.
 #
 
-sudo bash -c "cat >~/.xsession <<EOF
+if [ ! $(id -u) ] ; then
+    echo 'This script must be run with root privileges' >&2
+    exit 1
+fi
+
+bash -c "cat >~/.xsession <<EOF
 
 /usr/lib/gnome-session/gnome-session-binary --session=ubuntu &
 /usr/lib/x86_64-linux-gnu/unity/unity-panel-service &