diff --git a/daemon/README.rst b/daemon/README.rst
index 3ec8c8025d6ba94e30a32dc969b41792557ac8a7..13e5cc0c3bf492a73ac689382a5da0aa458299eb 100644
--- a/daemon/README.rst
+++ b/daemon/README.rst
@@ -230,6 +230,8 @@ Environment
    internal hostname, or the system's POSIX hostname (see
    gethostname(2)) if kresd's internal hostname is unset.
 
+   This affects ephemeral certificates for kresd serving DNS over TLS.
+
 .. function:: moduledir([dir])
 
    :return: Modules directory.