diff --git a/src/QUI/Memberships/Users/MembershipUser.php b/src/QUI/Memberships/Users/MembershipUser.php
index f7eff41935486694526b6f6da8599f68f6ccae7c..60fa68915439ec8e98151a5becbd08a848304935 100644
--- a/src/QUI/Memberships/Users/MembershipUser.php
+++ b/src/QUI/Memberships/Users/MembershipUser.php
@@ -951,11 +951,11 @@ public function getHistory(): array
     /**
      * Format date based on User Locale and duration mode
      *
-     * @param DateTime|string $date - Formatted date YYYY-MM-DD HH:MM:SS or \DateTime object
+     * @param DateTime|string|null $date - Formatted date YYYY-MM-DD HH:MM:SS or \DateTime object
      * @return string|false - formatted date or false on error
      * @throws Exception
      */
-    protected function formatDate(DateTime | string $date): bool | string
+    protected function formatDate(DateTime | string | null $date): bool | string
     {
         if (empty($date) || $date === '0000-00-00 00:00:00') {
             return false;