diff -u b/core/lib/Drupal/Component/Utility/FormattableString.php b/core/lib/Drupal/Component/Utility/FormattableString.php
--- b/core/lib/Drupal/Component/Utility/FormattableString.php
+++ b/core/lib/Drupal/Component/Utility/FormattableString.php
@@ -11,7 +11,9 @@
  * Provides a formattable string class.
  */
 class FormattableString implements SafeStringInterface {
+
   use PlaceholderTrait;
+  use ToStringTrait;
 
   /**
    * The safe string.
@@ -43,7 +45,7 @@
   /**
    * {@inheritdoc}
    */
-  public function __toString() {
+  public function render() {
     return static::placeholderFormat($this->string, $this->arguments);
   }