diff --git a/src/Symfony/Component/Form/FormBuilder.php b/src/Symfony/Component/Form/FormBuilder.php
index 8b5b919413..81c9ad5f6d 100644
--- a/src/Symfony/Component/Form/FormBuilder.php
+++ b/src/Symfony/Component/Form/FormBuilder.php
@@ -62,7 +62,7 @@ class FormBuilder extends FormConfigBuilder implements \IteratorAggregate, FormB
             throw new BadMethodCallException('FormBuilder methods cannot be accessed anymore once the builder is turned into a FormConfigInterface instance.');
         }
 
-        if ($child instanceof self) {
+        if ($child instanceof FormBuilderInterface) {
             $this->children[$child->getName()] = $child;
 
             // In case an unresolved child with the same name exists
@@ -72,7 +72,7 @@ class FormBuilder extends FormConfigBuilder implements \IteratorAggregate, FormB
         }
 
         if (!is_string($child) && !is_int($child)) {
-            throw new UnexpectedTypeException($child, 'string, integer or Symfony\Component\Form\FormBuilder');
+            throw new UnexpectedTypeException($child, 'string, integer or Symfony\Component\Form\FormBuilderInterface');
         }
 
         if (null !== $type && !is_string($type) && !$type instanceof FormTypeInterface) {
diff --git a/src/Symfony/Component/Form/Tests/FormBuilderTest.php b/src/Symfony/Component/Form/Tests/FormBuilderTest.php
index da691838c3..8c7b96587d 100644
--- a/src/Symfony/Component/Form/Tests/FormBuilderTest.php
+++ b/src/Symfony/Component/Form/Tests/FormBuilderTest.php
@@ -11,7 +11,9 @@
 
 namespace Symfony\Component\Form\Tests;
 
+use Symfony\Component\Form\ButtonBuilder;
 use Symfony\Component\Form\FormBuilder;
+use Symfony\Component\Form\SubmitButtonBuilder;
 
 class FormBuilderTest extends \PHPUnit_Framework_TestCase
 {
@@ -154,6 +156,12 @@ class FormBuilderTest extends \PHPUnit_Framework_TestCase
         $this->builder->create('foo');
     }
 
+    public function testAddButton()
+    {
+        $this->builder->add(new ButtonBuilder('reset'));
+        $this->builder->add(new SubmitButtonBuilder('submit'));
+    }
+
     public function testGetUnknown()
     {
         $this->setExpectedException('Symfony\Component\Form\Exception\InvalidArgumentException', 'The child with the name "foo" does not exist.');