diff --git a/lib/arke/system.ex b/lib/arke/system.ex
index 37fc78b..94525ac 100644
--- a/lib/arke/system.ex
+++ b/lib/arke/system.ex
@@ -37,6 +37,7 @@ defmodule Arke.System do
         unit.data.parameters
       end
 
+      def is_arke?(), do: nil
       def on_load(data, _persistence_fn), do: {:ok, data}
       def before_load(data, _persistence_fn), do: {:ok, data}
       def on_validate(arke, unit), do: {:ok, unit}