diff --git a/extension/Classes/Core/AbstractBuildForm.php b/extension/Classes/Core/AbstractBuildForm.php
index 6e314c12bf74f364ea2a7650714fdd18a8fd3e28..ea8612ef9dc9e20e2ef645a7cb41552e1d5f5dbc 100644
--- a/extension/Classes/Core/AbstractBuildForm.php
+++ b/extension/Classes/Core/AbstractBuildForm.php
@@ -1219,7 +1219,7 @@ abstract class AbstractBuildForm {
      * @throws \CodeException
      * @throws \UserFormException
      */
-    public static function getFormElementForJson(string $htmlFormElementName, mixed $value, array $formElement, mixed $wrap = '', mixed $optionIdx = 0, mixed $optionClass = ''): array {
+    public static function getFormElementForJson(string $htmlFormElementName, $value, array $formElement, $wrap = '', $optionIdx = 0,  $optionClass = ''): array {
         $addClassRequired = array();
 
         $json = HelperFormElement::getJsonFeMode($formElement[FE_MODE]); // disabled, required
diff --git a/extension/Classes/Core/Helper/DateTime.php b/extension/Classes/Core/Helper/DateTime.php
index 094a8eb45f90269df38e5c282f2379956b4a8059..cdf815b2267b144000210291e5652f0f88788614 100644
--- a/extension/Classes/Core/Helper/DateTime.php
+++ b/extension/Classes/Core/Helper/DateTime.php
@@ -281,9 +281,9 @@ class DateTime {
     /**
      * @param $defaultFormat
      * @param $feType
-     * @return mixed
+     * @return array|string
      */
-    private static function getDateTimeFormatQfq($defaultFormat, $feType): mixed {
+    private static function getDateTimeFormatQfq($defaultFormat, $feType) {
         switch ($defaultFormat['date']) {
             case FORMAT_DATE_INTERNATIONAL:
             case FORMAT_DATE_INTERNATIONAL_QFQ: