diff --git a/scripts/backup b/scripts/backup
index c9de6cd..f9762b6 100755
--- a/scripts/backup
+++ b/scripts/backup
@@ -65,7 +65,7 @@ backup_core_only=$(ynh_app_setting_get "$app" backup_core_only)
 # If backup_core_only have any value in the settings.yml file, do not backup the data directory
 if [ -z $backup_core_only ]
 then
-	ynh_backup "calibre_dir"
+	ynh_backup "$calibre_dir"
 else
 	echo "Data dir will not be saved, because backup_core_only is set." >&2
 fi