diff --git a/default.nix b/default.nix
index 83f2a16..374631b 100644
--- a/default.nix
+++ b/default.nix
@@ -838,6 +838,7 @@ in
     acmeCertificateName = mkOption {
       type = types.str;
       default = cfg.fqdn;
+      defaultText = literalExpression "config.mailserver.fqdn";
       example = "example.com";
       description = ''
           ({option}`mailserver.certificateScheme` == `acme`)