diff --git a/tasks/main.yml b/tasks/main.yml
index b95e00ea4089309fa303ebc1920495807bf1102b..c94a72e370b9328a03c2b917fb6cef34f2e20ddd 100644
--- a/tasks/main.yml
+++ b/tasks/main.yml
@@ -19,6 +19,6 @@
       dest='/etc/ssl/td-agent/key.pem'
       owner='root'
       group='root'
-      mode=644
+      mode='644'
 
   when: '"fluentd" not in excluded_roles'