diff --git a/README.md b/README.md
index ef19c12..31ee99b 100644
--- a/README.md
+++ b/README.md
@@ -94,7 +94,8 @@ domains = friendica.example.com
 
 You can also add Mastodon instances you trust. In addition to the configuration
 needed for Friendica nodes you have to add the `type = mastodon` entry to the
-config section.
+config section. *Please note* that the used API endpoint is not available on
+all Mastodon instances.
 
 Please note only suspended entries from the Mastodon blocklist will be added to
 the blocklist. Silenced entries will be ignored.