diff --git a/mail-server/nginx.nix b/mail-server/nginx.nix
index 5433f03..0ed22ab 100644
--- a/mail-server/nginx.nix
+++ b/mail-server/nginx.nix
@@ -49,7 +49,7 @@ in
         };
 
         security.acme.certs."${cfg.acmeCertificateName}" = {
-          extraDomainNames = cfg.certificateDomains;
+          extraDomainNames = lib.mkIf (cfg.certificateScheme == "acme") cfg.certificateDomains;
           reloadServices = [
             "postfix.service"
             "${dovecotUnitName}.service"