diff --git a/backup/backup.sh b/backup/backup.sh
index a5e848c..50452e9 100755
--- a/backup/backup.sh
+++ b/backup/backup.sh
@@ -3,16 +3,6 @@
 # execute script in its location folder
 cd $(dirname $0)
 
-deleteOldest() {
-  line_num=0
-  while IFS=  read -r -d $'\0'; do
-      if [ $line_num == 1 ]; then
-        $(rm -rf ${REPLY})
-      fi
-      ((line_num++))
-  done < <(find -maxdepth 1 -type d -print0 | sort -z)
-}
-
 # array of available collection names
 col=(app_user awarding decoration rank squad user promotion player war campaign)
 
@@ -35,14 +25,15 @@ do
   if [ -z "$1" ]
     then
       mongoexport --db cc --collection $i --out ${DATE}/collections/${i}.json;
-      if [ $(ls -l | grep -c ^d) -gt 5 ]; then
-        deleteOldest
-      fi
     else
       mongoimport --db cc --collection $i --drop --file ${1}/collections/${i}.json
   fi
 done
 
+if [ $(ls -lt --hide=backup.sh | wc -l) -gt 6 ]; then
+    $(rm "$(ls -t --hide=backup.sh | tail -1)")
+fi
+
 if [ -z "$1" ]
   then
     tar -zcf ${DATE}.tar.gz ${DATE}