diff --git a/lib/ash/type/module.ex b/lib/ash/type/module.ex
index e908ae47..d483605e 100644
--- a/lib/ash/type/module.ex
+++ b/lib/ash/type/module.ex
@@ -37,7 +37,7 @@ defmodule Ash.Type.Module do
     {:atomic, new_value}
   end
 
-  def apply_constraints(nil, _), do: :ok
+  def apply_constraints(nil, _), do: {:ok, nil}
 
   def apply_constraints(value, constraints) do
     []