diff --git a/src/Symfony/Component/Form/Extension/Core/Type/ChoiceType.php b/src/Symfony/Component/Form/Extension/Core/Type/ChoiceType.php
index 692f91e95c..83fe717f0d 100644
--- a/src/Symfony/Component/Form/Extension/Core/Type/ChoiceType.php
+++ b/src/Symfony/Component/Form/Extension/Core/Type/ChoiceType.php
@@ -166,7 +166,7 @@ class ChoiceType extends AbstractType
             $choices = null !== $options['choices'] ? $options['choices'] : array();
 
             // Reuse existing choice lists in order to increase performance
-            $hash = md5(json_encode(array($choices, $options['preferred_choices'])));
+            $hash = hash('sha256', serialize(array($choices, $options['preferred_choices'])));
 
             if (!isset($choiceListCache[$hash])) {
                 $choiceListCache[$hash] = new SimpleChoiceList($choices, $options['preferred_choices']);
diff --git a/src/Symfony/Component/Form/Tests/Extension/Core/Type/ChoiceTypeTest.php b/src/Symfony/Component/Form/Tests/Extension/Core/Type/ChoiceTypeTest.php
index 3da49dfa6a..2e99c2c774 100644
--- a/src/Symfony/Component/Form/Tests/Extension/Core/Type/ChoiceTypeTest.php
+++ b/src/Symfony/Component/Form/Tests/Extension/Core/Type/ChoiceTypeTest.php
@@ -1216,6 +1216,47 @@ class ChoiceTypeTest extends \Symfony\Component\Form\Test\TypeTestCase
         ));
     }
 
+    // https://github.com/symfony/symfony/issues/10409
+    public function testReuseNonUtf8ChoiceLists()
+    {
+        $form1 = $this->factory->createNamed('name', 'choice', null, array(
+            'choices' => array(
+                'meter' => 'm',
+                'millimeter' => 'mm',
+                'micrometer' => chr(181).'meter',
+            ),
+        ));
+
+        $form2 = $this->factory->createNamed('name', 'choice', null, array(
+            'choices' => array(
+                'meter' => 'm',
+                'millimeter' => 'mm',
+                'micrometer' => chr(181).'meter',
+            ),
+        ));
+
+        $form3 = $this->factory->createNamed('name', 'choice', null, array(
+            'choices' => array(
+                'meter' => 'm',
+                'millimeter' => 'mm',
+                'micrometer' => null,
+            ),
+        ));
+
+        // $form1 and $form2 use the same ChoiceList
+        $this->assertSame(
+            $form1->getConfig()->getOption('choice_list'),
+            $form2->getConfig()->getOption('choice_list')
+        );
+
+        // $form3 doesn't, but used to use the same when using json_encode()
+        // instead of serialize for the hashing algorithm
+        $this->assertNotSame(
+            $form1->getConfig()->getOption('choice_list'),
+            $form3->getConfig()->getOption('choice_list')
+        );
+    }
+
     public function testInitializeWithDefaultObjectChoice()
     {
         $obj1 = (object) array('value' => 'a', 'label' => 'A');