diff --git a/docker/prod/docker-compose.yml b/docker/prod/docker-compose.yml
index 38cac0e..fb7dfc6 100644
--- a/docker/prod/docker-compose.yml
+++ b/docker/prod/docker-compose.yml
@@ -4,6 +4,7 @@ services:
         ports:
             - "4567:8080"
         environment:
+            # Generate the APP_KEY with `echo "base64:$(openssl rand -base64 32)"`
             #- APP_KEY=
             - PHP_OPCACHE_ENABLE=1
             - TRMNL_PROXY_REFRESH_MINUTES=15