diff --git a/roles/kiwix/templates/kiwix.conf.j2 b/roles/kiwix/templates/kiwix.conf.j2
index 3132ba2e8..634102ef3 100644
--- a/roles/kiwix/templates/kiwix.conf.j2
+++ b/roles/kiwix/templates/kiwix.conf.j2
@@ -8,4 +8,9 @@ RedirectMatch ^{{ kiwix_alias_url }}$ {{ kiwix_url }}
 # 2018-08-31: SUCCEEDS in enabling http://box/kiwix/ & http://box/kiwix/zim & http://box/kiwix/zim/
 #ProxyPreserveHost On
 ProxyPass {{ kiwix_url }} http://127.0.0.1:{{ kiwix_port}}{{ kiwix_url }}
+
+# CLARIF: ProxyPassReverse rewrites internal links, that come back from proxy.
+# Whereas e.g. calibre-web.conf (and many others) use this, kiwix.conf doesn't
+# as kiwix itself prefixes URLs, thanks to --urlRootLocation=/kiwix/ in kiwix's
+# systemd file arising from roles/kiwix/templates/kiwix-serve.service.j2
 #ProxyPassReverse {{ kiwix_url }} http://127.0.0.1:{{ kiwix_port}}{{ kiwix_url }}