diff --git a/x b/x
index 7b1894d..16e9cc3 100644
--- a/x
+++ b/x
@@ -13,27 +13,27 @@ GIT_USER_MAIL=michael.grote@posteo.de
 GIT_REPO_REMOTE_NAME=origin
 
 # Checks
-if [ -z $GIT_REPO_PATH ] ; then
+if [ -z "$GIT_REPO_PATH" ] ; then
     echo "GIT_REPO_PATH is not set."
     exit 3
 fi
-if [ -z $GIT_REPO_BRANCH ] ; then
+if [ -z "$GIT_REPO_BRANCH" ] ; then
     echo "GIT_REPO_BRANCH is not set."
     exit 3
 fi
-if [ -z $GIT_USERNAME ] ; then
+if [ -z "$GIT_USERNAME" ] ; then
     echo "GIT_USERNAME is not set."
     exit 3
 fi
-if [ -z $GIT_USER_MAIL ] ; then
+if [ -z "$GIT_USER_MAIL" ] ; then
     echo "GIT_USER_MAIL is not set."
     exit 3
 fi
-if [ -z $GIT_REPO_REMOTE_NAME ] ; then
+if [ -z "$GIT_REPO_REMOTE_NAME" ] ; then
     echo "GIT_REPO_REMOTE_NAME is not set."
     exit 3
 fi
-if [ -z $DEVICES ] ; then
+if [ -z "$DEVICES" ] ; then
     echo "DEVICES is not set."
     exit 3
 fi