diff --git a/doc/misc/gnus.texi b/doc/misc/gnus.texi
index 7bcf334297..578273aede 100644
--- a/doc/misc/gnus.texi
+++ b/doc/misc/gnus.texi
@@ -21900,14 +21900,13 @@ About mairix
 @uref{http://www.rpcurnow.force9.co.uk/mairix/index.html}
 
 Though mairix might not be as flexible as other search tools like
-swish++ or namazu, which you can use via the @code{nnir} back end, it
-has the prime advantage of being incredibly fast.  On current systems, it
-can easily search through headers and message bodies of thousands and
-thousands of mails in well under a second.  Building the database
-necessary for searching might take a minute or two, but only has to be
-done once fully.  Afterwards, the updates are done incrementally and
-therefore are really fast, too.  Additionally, mairix is very easy to set
-up.
+swish++ or namazu, it has the prime advantage of being incredibly
+fast.  On current systems, it can easily search through headers and
+message bodies of thousands and thousands of mails in well under a
+second.  Building the database necessary for searching might take a
+minute or two, but only has to be done once fully.  Afterwards, the
+updates are done incrementally and therefore are really fast, too.
+Additionally, mairix is very easy to set up.
 
 For maximum speed though, mairix should be used with mails stored in
 @code{Maildir} or @code{MH} format (this includes the @code{nnml} back
@@ -22545,6 +22544,20 @@ nnmairix caveats
 
 @end itemize
 
+@node nnir
+@section Migrating from nnir
+
+@cindex nnir
+
+Gnus' previous search engine was called nnir, and is now obsolete.  If
+you've upgraded Emacs and are now getting obsolete-variable warnings
+about @code{nnir-*} variables, migration is fairly straightforward.
+In addition to the variables raised by the warnings, all previous
+engine-specific variables can be updated by simply replacing the
+@code{nnir-} prefix with @code{gnus-search-}.  For instance,
+@code{nnir-notmuch-program} is now @code{gnus-search-notmuch-program}.
+
+
 @iftex
 @iflatex
 @chapter Message