diff --git a/src/Symfony/Component/Form/Extension/Core/DataMapper/PropertyPathMapper.php b/src/Symfony/Component/Form/Extension/Core/DataMapper/PropertyPathMapper.php
index 96078ce20b58..5f1ae2d2e836 100644
--- a/src/Symfony/Component/Form/Extension/Core/DataMapper/PropertyPathMapper.php
+++ b/src/Symfony/Component/Form/Extension/Core/DataMapper/PropertyPathMapper.php
@@ -23,22 +23,24 @@ class PropertyPathMapper implements DataMapperInterface
      */
     public function mapDataToForms($data, array $forms)
     {
-        if (!empty($data) && !is_array($data) && !is_object($data)) {
+        if (null === $data || array() === $data) {
+            return;
+        }
+
+        if (!is_array($data) && !is_object($data)) {
             throw new UnexpectedTypeException($data, 'object, array or empty');
         }
 
-        if (!empty($data)) {
-            $iterator = new VirtualFormAwareIterator($forms);
-            $iterator = new \RecursiveIteratorIterator($iterator);
+        $iterator = new VirtualFormAwareIterator($forms);
+        $iterator = new \RecursiveIteratorIterator($iterator);
 
-            foreach ($iterator as $form) {
-                /* @var FormInterface $form */
-                $propertyPath = $form->getPropertyPath();
-                $config = $form->getConfig();
+        foreach ($iterator as $form) {
+            /* @var FormInterface $form */
+            $propertyPath = $form->getPropertyPath();
+            $config = $form->getConfig();
 
-                if (null !== $propertyPath && $config->getMapped()) {
-                    $form->setData($propertyPath->getValue($data));
-                }
+            if (null !== $propertyPath && $config->getMapped()) {
+                $form->setData($propertyPath->getValue($data));
             }
         }
     }
@@ -48,6 +50,14 @@ public function mapDataToForms($data, array $forms)
      */
     public function mapFormsToData(array $forms, &$data)
     {
+        if (null === $data) {
+            return;
+        }
+
+        if (!is_array($data) && !is_object($data)) {
+            throw new UnexpectedTypeException($data, 'object, array or empty');
+        }
+
         $iterator = new VirtualFormAwareIterator($forms);
         $iterator = new \RecursiveIteratorIterator($iterator);
 
diff --git a/src/Symfony/Component/Form/Form.php b/src/Symfony/Component/Form/Form.php
index ee566feff91b..58135fed5015 100644
--- a/src/Symfony/Component/Form/Form.php
+++ b/src/Symfony/Component/Form/Form.php
@@ -15,6 +15,7 @@
 use Symfony\Component\Form\Exception\AlreadyBoundException;
 use Symfony\Component\Form\Exception\UnexpectedTypeException;
 use Symfony\Component\Form\Exception\TransformationFailedException;
+use Symfony\Component\Form\Util\FormUtil;
 use Symfony\Component\Form\Util\PropertyPath;
 use Symfony\Component\HttpFoundation\Request;
 use Symfony\Component\EventDispatcher\EventDispatcherInterface;
@@ -352,7 +353,7 @@ public function setData($modelData)
         $viewData = $this->normToView($normData);
 
         // Validate if view data matches data class (unless empty)
-        if ('' !== $viewData && null !== $viewData) {
+        if (!FormUtil::isEmpty($viewData)) {
             $dataClass = $this->config->getDataClass();
 
             $actualType = is_object($viewData) ? 'an instance of class ' . get_class($viewData) : ' a(n) ' . gettype($viewData);
@@ -492,12 +493,12 @@ public function bind($submittedData)
         // since forms without children may also be compound.
         // (think of empty collection forms)
         if ($this->config->getCompound()) {
-            if (null === $submittedData || '' === $submittedData) {
-                $submittedData = array();
-            }
-
             if (!is_array($submittedData)) {
-                throw new UnexpectedTypeException($submittedData, 'array');
+                if (!FormUtil::isEmpty($submittedData)) {
+                    throw new UnexpectedTypeException($submittedData, 'array');
+                }
+
+                $submittedData = array();
             }
 
             foreach ($this->children as $name => $child) {
@@ -520,7 +521,7 @@ public function bind($submittedData)
             $viewData = $this->getViewData();
         }
 
-        if (null === $viewData || '' === $viewData) {
+        if (FormUtil::isEmpty($viewData)) {
             $emptyData = $this->config->getEmptyData();
 
             if ($emptyData instanceof \Closure) {
@@ -532,7 +533,7 @@ public function bind($submittedData)
         }
 
         // Merge form data from children into existing view data
-        if ($this->config->getCompound() && null !== $viewData) {
+        if ($this->config->getCompound()) {
             $this->config->getDataMapper()->mapFormsToData($this->children, $viewData);
         }
 
@@ -701,7 +702,7 @@ public function isEmpty()
             }
         }
 
-        return array() === $this->modelData || null === $this->modelData || '' === $this->modelData;
+        return FormUtil::isEmpty($this->modelData) || array() === $this->modelData;
     }
 
     /**
@@ -1048,9 +1049,12 @@ private function normToModel($value)
      */
     private function normToView($value)
     {
-        if (!$this->config->getViewTransformers()) {
-            // Scalar values should always be converted to strings to
-            // facilitate differentiation between empty ("") and zero (0).
+        // Scalar values should  be converted to strings to
+        // facilitate differentiation between empty ("") and zero (0).
+        // Only do this for simple forms, as the resulting value in
+        // compound forms is passed to the data mapper and thus should
+        // not be converted to a string before.
+        if (!$this->config->getViewTransformers() && !$this->config->getCompound()) {
             return null === $value || is_scalar($value) ? (string) $value : $value;
         }
 
diff --git a/src/Symfony/Component/Form/Util/FormUtil.php b/src/Symfony/Component/Form/Util/FormUtil.php
index 251ebd040e77..868dab9610a5 100644
--- a/src/Symfony/Component/Form/Util/FormUtil.php
+++ b/src/Symfony/Component/Form/Util/FormUtil.php
@@ -219,4 +219,23 @@ static public function isChoiceSelected($choice, $value)
 
         return $choice === $value;
     }
+
+    /**
+     * Returns whether the given data is empty.
+     *
+     * This logic is reused multiple times throughout the processing of
+     * a form and needs to be consistent. PHP's keyword `empty` cannot
+     * be used as it also considers 0 and "0" to be empty.
+     *
+     * @param  mixed $data
+     *
+     * @return Boolean
+     */
+    static public function isEmpty($data)
+    {
+        // Should not do a check for array() === $data!!!
+        // This method is used in occurrences where arrays are
+        // not considered to be empty, ever.
+        return null === $data || '' === $data;
+    }
 }