          do: :ok
   end
 
-  defp validate_by(:atom, _, _, _), do: :ok
+  defp validate_by(:boolean, _schema, _value, _opts), do: :ok
+
+  defp validate_by(nil, _schema, _value, _opts), do: :ok
+
+  defp validate_by(:atom, _schema, _value, _opts), do: :ok
 
   #
   # Schema type handling

         do: :ok
  end

  defp validate_by(nil, _schema, nil, _opts), do: :ok

  defp validate_by(nil, schema, value, _opts),
    do: {:error, %{value: value, type: schema.type}}

  defp validate_by(:tuple, schema, value, opts),
    do: validate_by(:list, schema, value, opts)

         do: :ok
  end

  defp validate_by(:integer, schema, value, opts),
    do: validate_by(:number, schema, value, opts)

