diff --git a/flake.nix b/flake.nix
index edf1bbd..acb1a49 100644
--- a/flake.nix
+++ b/flake.nix
@@ -170,6 +170,7 @@
 
       perSystem = { config, pkgs, inputs', ... }: {
         treefmt = {
+          package = pkgs.treefmt1;
           inherit (config.flake-root) projectRootFile;
 
           programs = {
diff --git a/system/nixos/weewx.nix b/system/nixos/weewx.nix
index 85fe455..77e67d8 100644
--- a/system/nixos/weewx.nix
+++ b/system/nixos/weewx.nix
@@ -41,6 +41,27 @@ in
         Group = "weewx";
         ExecStart = "${pkg}/bin/weewxd --config=${config.age.secrets.weewx-config.path}";
         ExecStopPost = "-!${lib.getExe pkgs.umount} ${home}/weewx-data";
+
+        CapabilityBoundingSet = [ "" ];
+        DeviceAllow = [ "" ];
+        LockPersonality = true;
+        PrivateDevices = true;
+        PrivateUsers = true;
+        ProcSubset = "pid";
+        ProtectClock = true;
+        ProtectControlGroups = true;
+        ProtectHome = true;
+        ProtectHostname = true;
+        ProtectKernelLogs = true;
+        ProtectKernelModules = true;
+        ProtectKernelTunables = true;
+        ProtectProc = "invisible";
+        RestrictAddressFamilies = [ "AF_INET" "AF_INET6" "AF_UNIX" ];
+        RestrictNamespaces = true;
+        RestrictRealtime = true;
+        RestrictSUIDSGID = true;
+        SystemCallArchitectures = "native";
+        SystemCallFilter = [ "@system-service" "~@privileged" "~@resources" ];
       };
     };