diff --git a/README.md b/README.md
index bf19178..bf99965 100644
--- a/README.md
+++ b/README.md
@@ -412,7 +412,7 @@ Example commands:
 
 ### Relay bridge
 
-Bridges two or more Matrix rooms together via relaybot. 
+Bridges two or more Matrix rooms together via relaybot.
 
 Note: Room ID is not same as room alias! Rooms can exist without aliases so ID's are more flexible. Room id is usually in format !123LotOfRandomChars:server.org
 
@@ -518,7 +518,7 @@ docker-compose up
 ## Env variables
 
 `MATRIX_USER`, `MATRIX_ACCESS_TOKEN` and `MATRIX_SERVER` should be self-explanatory.
-Set `JOIN_ON_INVITE` to anything if you want the bot to join invites automatically (do not set it if you don't want it to join).
+Set `JOIN_ON_INVITE` (default true) to false if you don't want the bot automatically joining rooms.
 
 You can get access token by logging in with Riot and looking from Settings / Help & About.
 
diff --git a/bot.py b/bot.py
index 6fdf63f..3843443 100755
--- a/bot.py
+++ b/bot.py
@@ -391,7 +391,7 @@ class Bot:
         if matrix_server and self.matrix_user and bot_owners and access_token:
             self.client = AsyncClient(matrix_server, self.matrix_user, ssl = matrix_server.startswith("https://"))
             self.client.access_token = access_token
-            self.join_on_invite = join_on_invite is not None
+            self.join_on_invite = (join_on_invite or '').lower() == 'true'
             self.leave_empty_rooms = (leave_empty_rooms or 'true').lower() == 'true'
             self.owners = bot_owners.split(',')
             self.owners_only = owners_only