diff --git a/mongodb/BSON/UTCDateTime.php b/mongodb/BSON/UTCDateTime.php
index 5acc58eb5..00b08d015 100644
--- a/mongodb/BSON/UTCDateTime.php
+++ b/mongodb/BSON/UTCDateTime.php
@@ -26,6 +26,13 @@ public static function __set_state(array $properties) {}
      */
     final public function toDateTime(): \DateTime {}
 
+    /**
+     * Returns the DateTimeImmutable representation of this UTCDateTime
+     * @since 1.20.0
+     * @link https://php.net/manual/en/mongodb-bson-utcdatetime.todatetimeimmutable.php
+     */
+    final public function toDateTimeImmutable(): \DateTimeImmutable {}
+
     /**
      * Returns the string representation of this UTCDateTime
      * @link https://php.net/manual/en/mongodb-bson-utcdatetime.tostring.php