diff --git a/README.md b/README.md
index 3a7bd5e..cda983c 100644
--- a/README.md
+++ b/README.md
@@ -27,6 +27,8 @@ systemctl start netns-nat@helloworld
 chnetns helloworld ip address
 ```
 
+Note: Network interface names are derived from the netns name, so do not create netns names longer than 12 characters. 
+
 ## NS Types
 
 ### Basic (`netns@.service`)