diff --git a/nixos/modules/services/monitoring/prometheus/exporters.nix b/nixos/modules/services/monitoring/prometheus/exporters.nix
index 59748efe0ded..a5492d972f15 100644
--- a/nixos/modules/services/monitoring/prometheus/exporters.nix
+++ b/nixos/modules/services/monitoring/prometheus/exporters.nix
@@ -84,7 +84,8 @@ let
     };
     firewallFilter = mkOption {
       type = types.str;
-      default = "-p tcp -m tcp --dport ${toString port}";
+      default = "-p tcp -m tcp --dport ${toString cfg.${name}.port}";
+      defaultText = "-p tcp -m tcp --dport ${toString port}";
       example = literalExample ''
         "-i eth0 -p tcp -m tcp --dport ${toString port}"
       '';