diff -u b/core/lib/Drupal/Component/Datetime/DateTimePlus.php b/core/lib/Drupal/Component/Datetime/DateTimePlus.php
--- b/core/lib/Drupal/Component/Datetime/DateTimePlus.php
+++ b/core/lib/Drupal/Component/Datetime/DateTimePlus.php
@@ -93,6 +93,8 @@
 
   /**
    * The DateTime object.
+   *
+   * @var \DateTime
    */
   protected $dateTimeObject = NULL;
 
@@ -282,16 +284,30 @@
   }
 
   /**
-   * Passes through all unknown calls onto the DateTime object.
+   * {@inheritdoc}
    */
   public function __call($method, $args) {
+    if (!isset($this->dateTimeObject)) {
+      throw new Exception('DateTime object not set.');
+    }
+    if (!method_exists($this->dateTimeObject, $method)) {
+      throw new \BadMethodCallException(sprintf('Call to undefined method %s::%s()', get_class($this), $method));
+    }
     return call_user_func_array(array($this->dateTimeObject, $method), $args);
   }
 
   /**
-   * PHP magic __clone() method.
-   *
-   * Deep-clones the DateTime object we're wrapping.
+   * {@inheritdoc}
+   */
+  public static function __callStatic($method, $args) {
+    if (!method_exists('\DateTime', $method)) {
+      throw new \BadMethodCallException(sprintf('Call to undefined method %s::%s()', get_called_class(), $method));
+    }
+    return call_user_func_array(array('\DateTime', $method), $args);
+  }
+
+  /**
+   * {@inheritdoc}
    */
   public function __clone() {
     $this->dateTimeObject = clone($this->dateTimeObject);
@@ -370,11 +386,7 @@
    * @see http://us3.php.net/manual/en/time.getlasterrors.php
    */
   public function checkErrors() {
-    if (!isset($this->dateTimeObject)) {
-      return;
-    }
-
-    $errors = $this->dateTimeObject->getLastErrors();
+    $errors = self::getLastErrors();
     if (!empty($errors['errors'])) {
       $this->errors += $errors['errors'];
     }