diff --git a/runtime/optwin.vim b/runtime/optwin.vim
index 7392b53..056d24c 100644
--- a/runtime/optwin.vim
+++ b/runtime/optwin.vim
@@ -365,6 +365,9 @@
 call append("$", "number\tshow the line number for each line")
 call append("$", "\t(local to window)")
 call <SID>BinOptionL("nu")
+call append("$", "relativenumber\tshow the relative line number for each line")
+call append("$", "\t(local to window)")
+call <SID>BinOptionL("rnu")
 if has("linebreak")
   call append("$", "numberwidth\tnumber of columns to use for the line number")
   call append("$", "\t(local to window)")