diff --git a/modules/restic/system.nix b/modules/restic/system.nix
index d69cc3c..82d2c99 100644
--- a/modules/restic/system.nix
+++ b/modules/restic/system.nix
@@ -87,7 +87,7 @@ in
       type = lib.types.nullOr lib.types.int;
       default = null;
     };
-    qos = (lib.mkEnableOption "QoS marking (DSCP AF12) of outgoing packets") // { default = !(lib.isNull cfg.uploadLimit); };
+    qos = (lib.mkEnableOption "QoS marking (DSCP AF12) of outgoing packets") // { default = !(isNull cfg.uploadLimit); };
     prune = lib.mkEnableOption "pruning";
   };
 
@@ -119,13 +119,14 @@ in
         "--tag system"
         "--verbose"
       ] ++ lib.optional (cfg.uploadLimit != null) "--limit-upload=${toString cfg.uploadLimit}";
+    } // (lib.optionalAttrs cfg.qos {
       backupPrepareCommand = ''
         ${pkgs.nftables}/bin/nft -f ${qosRules}
       '';
       backupCleanupCommand = ''
         ${pkgs.nftables}/bin/nft delete table inet restic
       '';
-    };
+    });
 
     systemd.services."restic-backups-system".serviceConfig = {
       "Nice" = 10;