diff --git a/backup.sh b/backup.sh
index d3b4397..0a78d2b 100755
--- a/backup.sh
+++ b/backup.sh
@@ -2,31 +2,35 @@
 
 
 # backup directory
-backup_dir=backup
+SCRIPT_DIR="$( cd "$( dirname "${BASH_SOURCE[0]}" )" && pwd )"
+backup_dir=${SCRIPT_DIR}/backup
 
 # load variaables form config
-source openhab.conf
+source ${SCRIPT_DIR}/openhab.conf
 
 # current date
 DATE=$(date +"%Y%m%d_%H%M%S")
 
 # create backuop directories
-mkdir -p $backup_dir/conf
-mkdir -p $backup_dir/data/conf
-mkdir -p $backup_dir/data/addons
-mkdir -p $backup_dir/data/userdata
+mkdir -p ${backup_dir}/conf
+mkdir -p ${backup_dir}/data/conf
+mkdir -p ${backup_dir}/data/addons
+mkdir -p ${backup_dir}/data/userdata
 
 
 ## backup
 
 # main conf
-tar -cjf ${PWD}/${backup_dir}/conf/${DATE}.tbz2 openhab.conf
+tar -cjf ${backup_dir}/conf/${DATE}.tbz2 openhab.conf
 
 # openHAB conf
-tar -C data -cjf ${PWD}/${backup_dir}/data/conf/${DATE}.tbz2 conf
+tar -C data -cjf ${backup_dir}/data/conf/${DATE}.tbz2 conf
 
 # openHAB addons
-tar -C data -cjf ${PWD}/${backup_dir}/data/addons/${DATE}.tbz2 addons
+tar -C data -cjf ${backup_dir}/data/addons/${DATE}.tbz2 addons
 
 # openHAB userdata
-tar -C data -cjf ${PWD}/${backup_dir}/data/userdata/${DATE}.tbz2 userdata
+tar -C data -cjf ${backup_dir}/data/userdata/${DATE}.tbz2 userdata
+
+# delete all files older 30 days
+find ${backupDir} -iname "*.tbz2" -type f -mtime +30 -exec rm {} \; > /dev/null