diff --git a/zonebackuptofile.sh b/zonebackuptofile.sh
index 234cac2..09bf391 100755
--- a/zonebackuptofile.sh
+++ b/zonebackuptofile.sh
@@ -2,16 +2,19 @@
 
 usage()
 {
-    echo "Usage: $0 -z UUID" >&2
+    echo "Usage: $0 -z UUID -d days" >&2
     exit 1
 }
 
-while getopts "z:" opt;
+while getopts "z:d:" opt;
 do
     case "$opt" in
         z)
 	    UUID=$OPTARG
 	    ;;
+        d)
+        DAYS=$OPTARG
+        ;;
         *)
 	    usage
 	    ;;
@@ -24,6 +27,10 @@ if [ -z "${UUID}" ]; then
     usage
 fi
 
+if [ -z "${DAYS}" ]; then
+    usage
+fi
+
 BRAND=`/usr/sbin/vmadm get $UUID | json brand | tr -d '\n'`
 
 RUTADESTINO="/zones/tools/mounts"
@@ -47,8 +54,8 @@ if [ $? != 0 ]; then
     exit
 fi
 
-# mantenemos los backups de los ultimos dos dias
-find $RUTADESTINO/$UUID -type f -mtime +3 -delete
+# mantain backups of the last N days
+find $RUTADESTINO/$UUID -type f -mtime +$DAYS -delete
 
 snapshot()
 {