Resolves http://github.com/justinfrench/formtastic/issues/#issue/409

README.textile

@@ -517,7 +517,24 @@ If you want to add your own input types to encapsulate your own logic or interfa
 
 @Formtastic::SemanticFormHelper.builder = MyCustomBuilder@
 
+Be aware that you should either set the options on custom builder or require it after setting options on formtastic default builder.
 
+<pre>
+# OK
+Formtastic::SemanticFormBuilder.i18n_lookups_by_default = true
+require 'formtastic/my_custom_builder'
+Formtastic::SemanticFormHelper.builder = Formtastic::MyCustomBuilder
+
+# OK
+require 'formtastic/my_custom_builder'
+Formtastic::SemanticFormHelper.builder = Formtastic::MyCustomBuilder
+Formtastic::ExtendedFormBuilder.i18n_lookups_by_default = true
+
+# WRONG!
+require 'formtastic/my_custom_builder'
+Formtastic::SemanticFormBuilder.i18n_lookups_by_default = true
+Formtastic::SemanticFormHelper.builder = Formtastic::MyCustomBuilder
+</pre>
 
 
 h2. Status