diff --git a/package-postfix_filter/defaults/main.yml b/package-postfix_filter/defaults/main.yml
index ca0c3a3..ffb7036 100644
--- a/package-postfix_filter/defaults/main.yml
+++ b/package-postfix_filter/defaults/main.yml
@@ -18,7 +18,7 @@ remote_block_lists:
   - cbl.abuseat.org
 
 # Enable TLS (literal yes/no only) and, if yes, the cert and key files
-tls_enabled: yes
+tls_enabled: "yes"
 tls_cert: "/etc/ssl/{{ ansible_fqdn }}.crt"
 tls_key: "/etc/ssl/{{ ansible_fqdn }}.key"