diff --git a/runtime/optwin.vim b/runtime/optwin.vim
index 70c56f5..73de9e1 100644
--- a/runtime/optwin.vim
+++ b/runtime/optwin.vim
@@ -348,6 +348,8 @@
 call append("$", " \tset co=" . &co)
 call append("$", "lines\tnumber of lines in the display")
 call append("$", " \tset lines=" . &lines)
+call append("$", "window\tnumber of lines to scroll for CTRL-F and CTRL-B")
+call append("$", " \tset window=" . &window)
 call append("$", "lazyredraw\tdon't redraw while executing macros")
 call <SID>BinOptionG("lz", &lz)
 if has("reltime")