diff --git a/README.md b/README.md
index 4a7bda1..b4abbe2 100644
--- a/README.md
+++ b/README.md
@@ -38,6 +38,7 @@ And the following are optional.
 * `HUBOT_IRC_UNFLOOD`
 * `HUBOT_IRC_DEBUG`
 * `HUBOT_IRC_USESSL`
+* `HUBOT_IRC_PRIVATE`
 
 ### IRC Server