diff --git a/src/Symfony/Component/Form/FormFactory.php b/src/Symfony/Component/Form/FormFactory.php
index f7160d5507..048705f142 100644
--- a/src/Symfony/Component/Form/FormFactory.php
+++ b/src/Symfony/Component/Form/FormFactory.php
@@ -101,12 +101,12 @@ class FormFactory implements FormFactoryInterface
         }
 
         if ($type instanceof FormTypeInterface) {
-            @trigger_error('Passing type instances to FormBuilder::add(), Form::add() or the FormFactory is deprecated since version 2.8 and will not be supported in 3.0. Use the fully-qualified type class name instead.', E_USER_DEPRECATED);
+            @trigger_error(sprintf('Passing type instances to FormBuilder::add(), Form::add() or the FormFactory is deprecated since version 2.8 and will not be supported in 3.0. Use the fully-qualified type class name instead (%s).', get_class($type)), E_USER_DEPRECATED);
             $type = $this->resolveType($type);
         } elseif (is_string($type)) {
             $type = $this->registry->getType($type);
         } elseif ($type instanceof ResolvedFormTypeInterface) {
-            @trigger_error('Passing type instances to FormBuilder::add(), Form::add() or the FormFactory is deprecated since version 2.8 and will not be supported in 3.0. Use the fully-qualified type class name instead.', E_USER_DEPRECATED);
+            @trigger_error(sprintf('Passing type instances to FormBuilder::add(), Form::add() or the FormFactory is deprecated since version 2.8 and will not be supported in 3.0. Use the fully-qualified type class name instead (%s).', get_class($type->getInnerType())), E_USER_DEPRECATED);
         } else {
             throw new UnexpectedTypeException($type, 'string, Symfony\Component\Form\ResolvedFormTypeInterface or Symfony\Component\Form\FormTypeInterface');
         }