diff --git a/lib/DateTimeImmutable.php b/lib/DateTimeImmutable.php
index 346d952f..5cedd24a 100644
--- a/lib/DateTimeImmutable.php
+++ b/lib/DateTimeImmutable.php
@@ -51,7 +51,7 @@ public function getInnerDateTime(): \DateTimeImmutable
      * @param \DateTimeZone|null $timezone
      * @throws DatetimeException
      */
-    public static function createFromFormat($format, $time, $timezone = null)
+    public static function createFromFormat($format, $time, $timezone = null): self
     {
         $datetime = \DateTimeImmutable::createFromFormat($format, $time, $timezone);
         if ($datetime === false) {