diff --git a/README.md b/README.md
index fde8202..f2b309e 100644
--- a/README.md
+++ b/README.md
@@ -113,6 +113,8 @@ docker run -d \
   hastic/server
 ```
 
+**Make sure that HASTIC_PORT is opened in your firewall. Default value is 8000.**
+
 ### Changelog
 
 ### [0.2.2-alpha] - 2018-09-12