diff --git a/core/lib/Drupal/Core/Template/Attribute.php b/core/lib/Drupal/Core/Template/Attribute.php
index dc5fb0a..3967cf8 100644
--- a/core/lib/Drupal/Core/Template/Attribute.php
+++ b/core/lib/Drupal/Core/Template/Attribute.php
@@ -99,8 +99,9 @@ protected function createAttributeValue($name, $value) {
     elseif (!is_object($value)) {
       $value = new AttributeString($name, $value);
     }
-    elseif (is_object($value) && !($value instanceof AttributeValueBase) && !method_exists($value, '__toString')) {
-      throw new Exception(t('"@attribute_name" attribute value of type "@class" can not be converted to string', array(
+    // Provide a better exception message when invalid object is passed as value.
+    elseif (is_object($value) && !method_exists($value, '__toString')) {
+      throw new \Exception(t('"@attribute_name" attribute value of type "@class" can not be converted to string', array(
         '@attribute_name' => $name,
         '@class' => get_class($value)
       )));