diff --git a/doc/ledger3.texi b/doc/ledger3.texi
index f89bf3c2..54b05f30 100644
--- a/doc/ledger3.texi
+++ b/doc/ledger3.texi
@@ -2,6 +2,10 @@
 
 @setfilename ledger3.info
 @settitle Ledger: Command-Line Accounting
+@c Define a new index for options.
+@defcodeindex op
+@c Put options in function index.
+@syncodeindex op fn
 
 @c Before release, run C-u C-c C-u C-a (texinfo-all-menus-update with
 @c a prefix arg).  This updates the node pointers, which texinfmt.el