diff --git a/src/Symfony/Bundle/FrameworkBundle/Form/PhpEngineTheme.php b/src/Symfony/Bundle/FrameworkBundle/Form/PhpEngineTheme.php
index 321b4e5670..85c0adfe77 100644
--- a/src/Symfony/Bundle/FrameworkBundle/Form/PhpEngineTheme.php
+++ b/src/Symfony/Bundle/FrameworkBundle/Form/PhpEngineTheme.php
@@ -48,8 +48,10 @@ class PhpEngineTheme implements FormThemeInterface
         $this->templateDir = $templateDir;
     }
 
-    public function render(array $blocks, $section, array $parameters)
+    public function render($blocks, $section, array $parameters)
     {
+        $blocks = (array)$blocks;
+
         foreach ($blocks as &$block) {
             $block = $block.'_'.$section;
 
diff --git a/src/Symfony/Component/Form/Renderer/Theme/FormThemeInterface.php b/src/Symfony/Component/Form/Renderer/Theme/FormThemeInterface.php
index 4a94ad6e67..f933844f13 100644
--- a/src/Symfony/Component/Form/Renderer/Theme/FormThemeInterface.php
+++ b/src/Symfony/Component/Form/Renderer/Theme/FormThemeInterface.php
@@ -13,5 +13,5 @@ namespace Symfony\Component\Form\Renderer\Theme;
 
 interface FormThemeInterface
 {
-    function render(array $blocks, $section, array $parameters);
+    function render($blocks, $section, array $parameters);
 }
diff --git a/src/Symfony/Component/Form/Renderer/Theme/PhpTheme.php b/src/Symfony/Component/Form/Renderer/Theme/PhpTheme.php
index cd2340b2b5..e2596655d4 100644
--- a/src/Symfony/Component/Form/Renderer/Theme/PhpTheme.php
+++ b/src/Symfony/Component/Form/Renderer/Theme/PhpTheme.php
@@ -33,8 +33,10 @@ class PhpTheme implements FormThemeInterface
         $this->charset = $charset;
     }
 
-    public function render(array $blocks, $section, array $parameters)
+    public function render($blocks, $section, array $parameters)
     {
+        $blocks = (array)$blocks;
+
         foreach ($blocks as $block) {
             $method = $block.'_'.$section;
 
diff --git a/src/Symfony/Component/Form/Renderer/Theme/TwigTheme.php b/src/Symfony/Component/Form/Renderer/Theme/TwigTheme.php
index a1eccd0395..a7b2417aa0 100644
--- a/src/Symfony/Component/Form/Renderer/Theme/TwigTheme.php
+++ b/src/Symfony/Component/Form/Renderer/Theme/TwigTheme.php
@@ -73,10 +73,12 @@ class TwigTheme implements FormThemeInterface
         return array_unique($names);
     }
 
-    public function render(array $blocks, $section, array $parameters)
+    public function render($blocks, $section, array $parameters)
     {
         $this->initialize();
 
+        $blocks = (array)$blocks;
+
         foreach ($blocks as $block) {
             $blockName = $block.'__'.$section;