diff --git a/nixos/modules/services/mail/opensmtpd.nix b/nixos/modules/services/mail/opensmtpd.nix
index d1f944ac88eb..2fc628a64aeb 100644
--- a/nixos/modules/services/mail/opensmtpd.nix
+++ b/nixos/modules/services/mail/opensmtpd.nix
@@ -113,11 +113,13 @@ in
       source = "${cfg.package}/bin/smtpctl";
     };
 
-    services.mail.sendmailSetuidWrapper = lib.mkIf cfg.setSendmail
-      (security.wrappers.smtpctl // {
+    services.mail.sendmailSetuidWrapper = lib.mkIf cfg.setSendmail (
+      security.wrappers.smtpctl
+      // {
         source = "${sendmail}/bin/sendmail";
         program = "sendmail";
-      });
+      }
+    );
 
     systemd.tmpfiles.rules = [
       "d /var/spool/smtpd 711 root - - -"
diff --git a/nixos/tests/opensmtpd.nix b/nixos/tests/opensmtpd.nix
index 483464362fa7..e1c26a7c6775 100644
--- a/nixos/tests/opensmtpd.nix
+++ b/nixos/tests/opensmtpd.nix
@@ -16,24 +16,26 @@ import ./make-test-python.nix {
             }
           ];
         };
-        environment.systemPackages = let
-          testSendmail = pkgs.writeScriptBin "test-sendmail" ''
-            #!/bin/sh
-            set -euxo pipefail
-            echo "========= SENDING" >&2
-            ${pkgs.system-sendmail}/bin/sendmail -v -f alice@smtp1 bob@smtp2 >&2 <<EOF
-            From: alice@smtp1
-            To: bob@smtp2
-            Subject: Sendmail Test
+        environment.systemPackages =
+          let
+            testSendmail = pkgs.writeScriptBin "test-sendmail" ''
+              #!/bin/sh
+              set -euxo pipefail
+              echo "========= SENDING" >&2
+              ${pkgs.system-sendmail}/bin/sendmail -v -f alice@smtp1 bob@smtp2 >&2 <<EOF
+              From: alice@smtp1
+              To: bob@smtp2
+              Subject: Sendmail Test
 
-            Hello World
-            EOF
-            echo "=========== FINISHED SENDING" >&2
-          '';
-        in [
-          pkgs.opensmtpd
-          testSendmail
-        ];
+              Hello World
+              EOF
+              echo "=========== FINISHED SENDING" >&2
+            '';
+          in
+          [
+            pkgs.opensmtpd
+            testSendmail
+          ];
         services.opensmtpd = {
           enable = true;
           extraServerArgs = [ "-v" ];