diff --git a/runtime/optwin.vim b/runtime/optwin.vim
index c5e77af..941a63c 100644
--- a/runtime/optwin.vim
+++ b/runtime/optwin.vim
@@ -1,7 +1,7 @@
 " These commands create the option window.
 "
 " Maintainer:	The Vim Project <https://github.com/vim/vim>
-" Last Change:	2025 Apr 07
+" Last Change:	2025 Apr 24
 " Former Maintainer:	Bram Moolenaar <Bram@vim.org>
 
 " If there already is an option window, jump to that one.
@@ -1254,6 +1254,8 @@
 call <SID>OptionG("isf", &isf)
 call <SID>AddOption("isident", gettext("specifies the characters in an identifier"))
 call <SID>OptionG("isi", &isi)
+call <SID>AddOption("isexpand", gettext("defines trigger strings for complete_match()"))
+call append("$", "\t" .. s:local_to_buffer)
 call <SID>AddOption("iskeyword", gettext("specifies the characters in a keyword"))
 call append("$", "\t" .. s:local_to_buffer)
 call <SID>OptionL("isk")