diff --git a/README.md b/README.md
index 130b067..068352a 100644
--- a/README.md
+++ b/README.md
@@ -111,7 +111,7 @@ interface OptionInterface extends IteratorAggregate
      *
      * @template TAndThen
      *
-     * @param callable(TValue):TAndThen $function
+     * @param callable(TValue):self $function
      *
      * @return self<TAndThen|TValue>
      */