diff --git a/nixos/server/package-configs/firefox-sync/default.nix b/nixos/server/package-configs/firefox-sync/default.nix
index 2566296..6b83ed9 100644
--- a/nixos/server/package-configs/firefox-sync/default.nix
+++ b/nixos/server/package-configs/firefox-sync/default.nix
@@ -8,7 +8,10 @@ in {
   sops.secrets."sync-secrets".mode = "0440";
   sops.secrets."sync-secrets".owner = config.users.users.firefox-syncserver.name;
 
-  users.users.firefox-syncserver.extraGroups = [config.users.groups.keys.name];
+  users.users.firefox-syncserver = {
+    isSystemUser = true;
+    extraGroups = [config.users.groups.keys.name];
+  };
 
   services.mysql.package = pkgs.mariadb;
   services.firefox-syncserver = {