diff --git a/nixos/modules/services/monitoring/prometheus/exporters.nix b/nixos/modules/services/monitoring/prometheus/exporters.nix
index 74ad4bf1837f..5811cda11256 100644
--- a/nixos/modules/services/monitoring/prometheus/exporters.nix
+++ b/nixos/modules/services/monitoring/prometheus/exporters.nix
@@ -131,7 +131,7 @@ let
           inherit name port;
         } // extraOpts);
       } ({ config, ... }: mkIf config.openFirewall {
-        firewallFilter = mkOptionDefault "-p tcp -m tcp --dport ${toString config.port}";
+        firewallFilter = mkDefault "-p tcp -m tcp --dport ${toString config.port}";
       })];
       internal = true;
       default = {};