diff --git a/nixos/modules/services/mail/opensmtpd.nix b/nixos/modules/services/mail/opensmtpd.nix
index dc209e8add4e..ef7d53e7d927 100644
--- a/nixos/modules/services/mail/opensmtpd.nix
+++ b/nixos/modules/services/mail/opensmtpd.nix
@@ -111,7 +111,7 @@ in {
     };
 
     services.mail.sendmailSetuidWrapper = mkIf cfg.setSendmail
-      security.wrappers.smtpctl // { program = "sendmail"; };
+      (security.wrappers.smtpctl // { program = "sendmail"; });
 
     systemd.tmpfiles.rules = [
       "d /var/spool/smtpd 711 root - - -"