diff --git a/lib/panko/impl/attributes_writer/active_record/values_writer/writer.rb b/lib/panko/impl/attributes_writer/active_record/values_writer/writer.rb
index 726a370..d7e1c37 100644
--- a/lib/panko/impl/attributes_writer/active_record/values_writer/writer.rb
+++ b/lib/panko/impl/attributes_writer/active_record/values_writer/writer.rb
@@ -46,7 +46,12 @@ def write(writer, attribute, value)
         return
       end
 
-      # TODO: validate against arrays
+      if attribute.type.respond_to?(:subtype)
+        # TODO: test this.
+        writer.push_value(attribute.type.deserialize(value), key)
+        return
+      end
+
       written = case attribute.type.type
       when :string, :text, :uuid
         @string_writer.write(value, writer, key)