diff --git a/live-build/auto/config b/live-build/auto/config
index 08c06ac0..9a2cf6a9 100755
--- a/live-build/auto/config
+++ b/live-build/auto/config
@@ -878,7 +878,7 @@ EOF
 		;;
 esac
 
-if [ $PROJECT = ubuntu-server ] && [ ${SUBPROJECT:-} != live ]; then
+if [ $PROJECT = ubuntu-server ] && [ "${SUBPROJECT:-}" != live ]; then
 	cat > config/hooks/100-remove-fstab.chroot <<EOF
 #! /bin/sh
 rm -f /etc/fstab