diff --git a/mercurial/help/config.txt b/mercurial/help/config.txt
index caebe5e7f4bd990a366a34cf6771be3f74498f61_bWVyY3VyaWFsL2hlbHAvY29uZmlnLnR4dA==..08481e11462e94b1416d8103b0953f6184dd9620_bWVyY3VyaWFsL2hlbHAvY29uZmlnLnR4dA== 100644
--- a/mercurial/help/config.txt
+++ b/mercurial/help/config.txt
@@ -2050,7 +2050,8 @@
     Repository filter used when exchanging revisions with the peer.
 
     The default view (``served``) excludes secret and hidden changesets.
-    Another useful value is ``immutable`` (no draft, secret or hidden changesets).
+    Another useful value is ``immutable`` (no draft, secret or hidden
+    changesets). (EXPERIMENTAL)
 
 ``smtp``
 --------