diff --git a/README.md b/README.md
index e1e1a9f..95400d7 100644
--- a/README.md
+++ b/README.md
@@ -6,6 +6,7 @@ You can configure the application using environment variables:
 
 - `$ROUTE_INTERNAL` : Rewrite links to point back to the archive itself
 - `$DOWNLOAD_ON_DEMAND` : Download missing routes with monolith on demand
+- `$BLACKLIST_DOMAINS` : Blacklisted domains (Comma-seperated regex, example: `google.com,.*.youtube.com`)
 
 ## Usage
 Archived pages can be viewed at `/s/<domain>/<path..>`.