diff --git a/core/tests/Drupal/Tests/Core/StringTranslation/TranslationWrapperTest.php b/core/tests/Drupal/Tests/Core/StringTranslation/TranslationWrapperTest.php
index 91b941d..436a6b3 100644
--- a/core/tests/Drupal/Tests/Core/StringTranslation/TranslationWrapperTest.php
+++ b/core/tests/Drupal/Tests/Core/StringTranslation/TranslationWrapperTest.php
@@ -1,4 +1,5 @@
 <?php
+
 /**
  * @file
  * Contains \Drupal\Tests\Core\StringTranslation\TranslationWrapperTest.
@@ -35,9 +36,13 @@ class TranslationWrapperTest extends UnitTestCase {
   /**
    * Custom error handler that saves the last error.
    *
-   * @param $error_number
+   * We need this custom error handler because we cannot rely on the error to
+   * exception conversion as __toString is never allowed to leak any kind of
+   * exception.
+   *
+   * @param int $error_number
    *   The error number.
-   * @param $error_message
+   * @param string $error_message
    *   The error message.
    */
   public function errorHandler($error_number, $error_message) {