diff --git a/README.md b/README.md
index 065a4f0..4a636f7 100644
--- a/README.md
+++ b/README.md
@@ -68,7 +68,7 @@ Download Docker for OSX from the [Github Releases](https://github.com/boot2docke
 
 The canonical way to use Docker is with the aid of the boot2docker VM.  However, using the out of the box boot2docker doesn't give me control over my Vagrant instances (especially the lack of port forwarding).  So here's how to use boot2docker from a Vagrant instance.
 
-We use the [YungSang modified boot2docker instance](https://github.com/YungSang/boot2docker-vagrant-box) from the [Vagrant Cloud](https://vagrantcloud.com/yungsang/boxes/boot2docker):
+We use the [YungSang modified boot2docker instance](https://github.com/YungSang/boot2docker-vagrant-box) from the [Vagrant Cloud](https://vagrantcloud.com/yungsang/boxes/boot2docker) -- this opens up port forwarding to the network, so is not safe on public wifi:
 
 ```
 mkdir ~/boot2docker