diff --git a/create-image.sh b/create-image.sh
index d3393fd..a475cb7 100755
--- a/create-image.sh
+++ b/create-image.sh
@@ -25,6 +25,7 @@ if [[ -n "$1" ]]; then
     GUSER="^$1"
     if ! grep $GUSER /etc/shadow > /dev/null; then
         >&2 echo "$0: ERROR: unable to find user '$1'"
+        exit 1
     fi
 fi