diff --git a/UPGRADING b/UPGRADING
index 9fdfdb88f92..5d4a0023c29 100644
--- a/UPGRADING
+++ b/UPGRADING
@@ -65,6 +65,9 @@ PHP 8.3 UPGRADE NOTES
 - Standard:
   . E_NOTICEs emitted by unserialized() have been promoted to E_WARNING.
     RFC: https://wiki.php.net/rfc/improve_unserialize_error_handling
+  . array_pad() is now only limited by the maximum number of elements an array
+    can have. Before, it was only possible to add at most 1048576 elements at a
+    time.
 
 ========================================
 6. New Functions