diff --git a/core/lib/Drupal/Core/Config/Entity/ThirdPartySettingsTrait.php b/core/lib/Drupal/Core/Config/Entity/ThirdPartySettingsTrait.php
index 3f63794..b14bd87 100644
--- a/core/lib/Drupal/Core/Config/Entity/ThirdPartySettingsTrait.php
+++ b/core/lib/Drupal/Core/Config/Entity/ThirdPartySettingsTrait.php
@@ -58,7 +58,7 @@ public function setThirdPartySetting($module, $key, $value) {
    * @return mixed
    *   The value.
    */
-  public function getThirdPartySetting($module, $key, $default = NULL) {
+  public function getThirdPartySetting($module, $key, $default) {
     if (isset($this->third_party_settings[$module][$key])) {
       return $this->third_party_settings[$module][$key];
     }