diff --git a/files/backup.sh b/files/backup.sh
index 2589e7742b9be15378c50e602c1aeba95a10db64..14af2b361cf33495ce7b94c1027a6cfe7129f40a 100755
--- a/files/backup.sh
+++ b/files/backup.sh
@@ -10,7 +10,7 @@ if databases="$(mysql --defaults-file=/etc/mysql/mysqldump.cnf \
                       --execute 'show databases;' | grep -vx $filter)"
 then
     mysqldump --defaults-file=/etc/mysql/mysqldump.cnf
-              --databases $databases || \
+              --databases "$databases" || \
     echo "MySQL backup: Failed to backup."
 else
     echo "MySQL backup: No databases to backup."