diff --git a/core/lib/Drupal/Core/Database/Connection.php b/core/lib/Drupal/Core/Database/Connection.php
index c170814..7d12118 100644
--- a/core/lib/Drupal/Core/Database/Connection.php
+++ b/core/lib/Drupal/Core/Database/Connection.php
@@ -1249,6 +1249,8 @@ public function quote($string, $parameter_type = \PDO::PARAM_STR) {
    * {@inheritdoc}
    */
   public function serialize() {
+    // Just store the target and the key of the connection because this is all
+    // what drupal needs to get a proper connection running again.
     return serialize(array($this->target, $this->key));
   }
 
diff --git a/core/modules/system/lib/Drupal/system/Tests/Database/ConnectionTest.php b/core/modules/system/lib/Drupal/system/Tests/Database/ConnectionTest.php
index 983a539..18f4c86 100644
--- a/core/modules/system/lib/Drupal/system/Tests/Database/ConnectionTest.php
+++ b/core/modules/system/lib/Drupal/system/Tests/Database/ConnectionTest.php
@@ -125,14 +125,14 @@ function testConnectionOptions() {
   }
 
   /**
-   * Tests the serialization and deserialization of a database connection.
+   * Tests the serialization and unserialization of a database connection.
    */
-  function testConnectionSerialization() {
+  public function testConnectionSerialization() {
     $db = Database::getConnection('default', 'default');
 
     $serialized = serialize($db);
-    $deserialized = unserialize($serialized);
+    $unserialized = unserialize($serialized);
 
-    $this->assertIdenticalObject($db, $deserialized, 'Serializing and deserializing a connection returns an identical object.');
+    $this->assertIdenticalObject($db, $unserialized, 'Serializing and unserializing a connection returns an identical object.');
   }
 }
diff --git a/core/modules/system/lib/Drupal/system/Tests/Form/FormTest.php b/core/modules/system/lib/Drupal/system/Tests/Form/FormTest.php
index c662ec7..ef498e1 100644
--- a/core/modules/system/lib/Drupal/system/Tests/Form/FormTest.php
+++ b/core/modules/system/lib/Drupal/system/Tests/Form/FormTest.php
@@ -664,4 +664,13 @@ function testMultiFormSameNameErrorClass() {
     $this->assertFieldByXpath('//input[@id="edit-name" and contains(@class, "error")]', NULL, 'Error input form element class found for first element.');
     $this->assertNoFieldByXpath('//input[@id="edit-name--2" and contains(@class, "error")]', NULL, 'No error input form element class found for second element.');
   }
+
+  /**
+   * Tests a form with a form state storing a database connection.
+   */
+  public function testFormStateDatabaseConnection() {
+    $this->assertNoText(t('Database connection found'));
+    $this->drupalPost('form-test/form_state-database', array(), t('Submit'));
+    $this->assertText(t('Database connection found'));
+  }
 }
diff --git a/core/modules/system/tests/modules/form_test/form_test.module b/core/modules/system/tests/modules/form_test/form_test.module
index c7a85a3..afcc3f9 100644
--- a/core/modules/system/tests/modules/form_test/form_test.module
+++ b/core/modules/system/tests/modules/form_test/form_test.module
@@ -5,6 +5,8 @@
  * Helper module for the form API tests.
  */
 
+use Drupal\Core\Database\Connection;
+use Drupal\Core\Database\Database;
 use Drupal\form_test\Callbacks;
 use Drupal\form_test\FormTestObject;
 use Drupal\form_test\SystemConfigFormTestForm;
@@ -353,6 +355,13 @@ function form_test_menu() {
     'access callback' => TRUE,
   );
 
+  $items['form-test/form_state-database'] = array(
+    'title' => t('Form state with a database connection'),
+    'page callback' => 'drupal_get_form',
+    'page arguments' => array('form_test_form_state_database'),
+    'access callback' => TRUE,
+  );
+
   return $items;
 }
 
@@ -2466,3 +2475,36 @@ function form_test_group_vertical_tabs() {
   );
   return $form;
 }
+
+/**
+ * Builds a form which gets the database connection stored in the form state.
+ */
+function form_test_form_state_database($form, &$form_state) {
+
+  $form['text'] = array(
+    '#type' => 'textfield',
+    '#title' => t('Text field'),
+  );
+
+  $form['test_submit'] = array(
+    '#type' => 'submit',
+    '#value' => t('Submit'),
+  );
+
+  if (!isset($form_state['storage']['database'])) {
+    $form_state['storage']['database'] = Database::getConnection('default');
+  }
+  elseif ($form_state['storage']['database'] instanceof Connection) {
+    $form['database']['#markup'] = t('Database connection found');
+  }
+
+  return $form;
+}
+
+/**
+ * Form submit handler for database form_state test.
+ */
+function form_test_form_state_database_submit($form, &$form_state) {
+  $form_state['cache'] = TRUE;
+  $form_state['rebuild'] = FALSE;
+}