diff --git a/contrib/cron/btrbk-mail b/contrib/cron/btrbk-mail
index 66c1658..bf6bedb 100755
--- a/contrib/cron/btrbk-mail
+++ b/contrib/cron/btrbk-mail
@@ -5,6 +5,7 @@
 now=$(date +%Y%m%d)
 
 declare -A rsync_src rsync_dst rsync_log rsync_rsh rsync_opt
+declare -A sync_fs_onchange
 
 #####  start config section  #####