diff --git a/book/forms.rst b/book/forms.rst
index 0fde7985056..a3c9dbe9961 100644
--- a/book/forms.rst
+++ b/book/forms.rst
@@ -1021,6 +1021,29 @@ to the ``form()`` or the ``form_start()`` helper:
     a PUT, PATCH or DELETE request. Read the cookbook chapter
     ":doc:`/cookbook/routing/method_parameters`" for more information.
 
+.. note::
+
+  Now that the ``createForm()`` method requires the FQCN, you can no longer pass in *dynamic* ``__construct()`` arguments. This is not to be confused with :ref:`form-as-services`. To get 
+  around this, you will need to create the default options in the form class ``configureOptions()`` method::
+  
+    use Symfony\Component\OptionsResolver\OptionsResolver;
+    use Symfony\Component\Form\Extension\Core\Type\PasswordType;
+    use Symfony\Component\Form\Extension\Core\Type\TextType;
+
+    public function buildForm(FormBuilderInterface $builder, array $options)
+    {
+        $builder->add('username', TextType::class, array('required' => $options['username_required']));
+        $builder->add('password', PasswordType::class, array('required' => $options['password_required']));
+    }
+
+    public function configureOptions(OptionsResolver $resolver)
+    {
+        $resolver->setDefaults(array(
+            'username_required' => true,
+            'password_required' => false,
+        ));
+    }
+
 .. index::
    single: Forms; Creating form classes