diff --git a/learning_ompl/install-ompl-ubuntu.sh b/learning_ompl/install-ompl-ubuntu.sh
old mode 100644
new mode 100755
index 9df73d5..733ffcf
--- a/learning_ompl/install-ompl-ubuntu.sh
+++ b/learning_ompl/install-ompl-ubuntu.sh
@@ -3,7 +3,7 @@
 set -e
 
 if [ `id -u` == 0 ]; then
-    SUDO=
+    SUDO=''
     export DEBIAN_FRONTEND=noninteractive
     apt-get -y install lsb-release
 else