diff --git a/src/Symfony/Component/Form/ChoiceList/Factory/DefaultChoiceListFactory.php b/src/Symfony/Component/Form/ChoiceList/Factory/DefaultChoiceListFactory.php
index b7f37137d8..4fa757295a 100644
--- a/src/Symfony/Component/Form/ChoiceList/Factory/DefaultChoiceListFactory.php
+++ b/src/Symfony/Component/Form/ChoiceList/Factory/DefaultChoiceListFactory.php
@@ -329,6 +329,8 @@ class DefaultChoiceListFactory implements ChoiceListFactoryInterface
             return;
         }
 
+        $groupLabel = (string) $groupLabel;
+
         // Initialize the group views if necessary. Unnnecessarily built group
         // views will be cleaned up at the end of createView()
         if (!isset($preferredViews[$groupLabel])) {
diff --git a/src/Symfony/Component/Form/Tests/ChoiceList/Factory/DefaultChoiceListFactoryTest.php b/src/Symfony/Component/Form/Tests/ChoiceList/Factory/DefaultChoiceListFactoryTest.php
index e5112bf38f..34f9991e0d 100644
--- a/src/Symfony/Component/Form/Tests/ChoiceList/Factory/DefaultChoiceListFactoryTest.php
+++ b/src/Symfony/Component/Form/Tests/ChoiceList/Factory/DefaultChoiceListFactoryTest.php
@@ -77,6 +77,13 @@ class DefaultChoiceListFactoryTest extends \PHPUnit_Framework_TestCase
         return $this->obj1 === $object || $this->obj2 === $object ? 'Group 1' : 'Group 2';
     }
 
+    public function getGroupAsObject($object)
+    {
+        return $this->obj1 === $object || $this->obj2 === $object
+            ? new DefaultChoiceListFactoryTest_Castable('Group 1')
+            : new DefaultChoiceListFactoryTest_Castable('Group 2');
+    }
+
     protected function setUp()
     {
         $this->obj1 = (object) array('label' => 'A', 'index' => 'w', 'value' => 'a', 'preferred' => false, 'group' => 'Group 1', 'attr' => array());
@@ -581,6 +588,19 @@ class DefaultChoiceListFactoryTest extends \PHPUnit_Framework_TestCase
         $this->assertGroupedView($view);
     }
 
+    public function testCreateViewFlatGroupByObjectThatCanBeCastToString()
+    {
+        $view = $this->factory->createView(
+            $this->list,
+            array($this->obj2, $this->obj3),
+            null, // label
+            null, // index
+            array($this, 'getGroupAsObject')
+        );
+
+        $this->assertGroupedView($view);
+    }
+
     public function testCreateViewFlatGroupByAsClosure()
     {
         $obj1 = $this->obj1;
@@ -897,3 +917,18 @@ class DefaultChoiceListFactoryTest extends \PHPUnit_Framework_TestCase
         ), $view);
     }
 }
+
+class DefaultChoiceListFactoryTest_Castable
+{
+    private $property;
+
+    public function __construct($property)
+    {
+        $this->property = $property;
+    }
+
+    public function __toString()
+    {
+        return $this->property;
+    }
+}