diff --git a/core/lib/Drupal/Core/StringTranslation/TranslatableMarkup.php b/core/lib/Drupal/Core/StringTranslation/TranslatableMarkup.php
index dcff3fc3b2..4b4bb71139 100644
--- a/core/lib/Drupal/Core/StringTranslation/TranslatableMarkup.php
+++ b/core/lib/Drupal/Core/StringTranslation/TranslatableMarkup.php
@@ -127,6 +127,9 @@ class TranslatableMarkup extends FormattableMarkup {
    * @ingroup sanitization
    */
   public function __construct($string, array $arguments = [], array $options = [], TranslationInterface $string_translation = NULL) {
+    if(is_null($string)) {
+      $string = '';
+    }
     if (!is_string($string)) {
       $message = $string instanceof TranslatableMarkup ? '$string ("' . $string->getUntranslatedString() . '") must be a string.' : '$string ("' . (string) $string . '") must be a string.';
       throw new \InvalidArgumentException($message);