diff --git a/README.md b/README.md
index 1c8e86e..cb54181 100644
--- a/README.md
+++ b/README.md
@@ -6,12 +6,12 @@ Server ID (`SERVER_ID`) and remote servers (`SERVERS`) are provided as environme
 
 #### Server 1
 ```bash
-SERVER_ID=1 SERVERS="2:localhost:4001" PORT=4000 mix run --no-halt
+SERVER_ID=1 SERVERS="2:localhost:4001" PORT=4000 AUTH_KEY=your_secret_shared_key mix run --no-halt
 ```
 
 #### Server 2
 ```bash
-SERVER_ID=2 SERVERS="1:localhost:4000" PORT=4001 mix run --no-halt
+SERVER_ID=2 SERVERS="1:localhost:4000" PORT=4001 AUTH_KEY=your_secret_shared_key mix run --no-halt
 ```
 
 ### Sending messages