diff --git a/plugins/Fediverse/README.md b/plugins/Fediverse/README.md
index ad1683afb..5fa60a4bd 100644
--- a/plugins/Fediverse/README.md
+++ b/plugins/Fediverse/README.md
@@ -1 +1,22 @@
 Fetches information from ActivityPub servers.
+
+# Enabling Secure Fetch
+
+The default configuration works with most ActivityPub servers, but not
+all of them, because they require an HTTP Signature to fetch profiles
+and statuses.
+
+Because of how HTTP Signatures work, you need to add some configuration
+for Limnoria to support it.
+
+First, you should set `supybot.servers.http.port` to a port you want
+your bot to listen on (by default it's 8080). If there are already
+plugins using it (eg. if Fediverse is already running), you should
+either unload all of them and load them back, or restart your bot.
+
+Then, you must configure a reverse-proxy in front of your bot (eg. nginx),
+and it must support HTTPS.
+
+Finally, set `supybot.servers.http.publicUrl` to the public URL of this
+server (when opening this URL in your browser, it should show a page with
+a title like "Supybot web server index").