diff --git a/README.md b/README.md
index 4687239d..7738e618 100644
--- a/README.md
+++ b/README.md
@@ -11,6 +11,12 @@ We're setting out to change that.
 
 `try` lets you run a command and inspect its effects before changing your live system. `try` uses Linux's [namespaces (via `unshare`)](https://docs.kernel.org/userspace-api/unshare.html) and the [overlayfs](https://docs.kernel.org/filesystems/overlayfs.html) union filesystem.
 
+Please note that `try` is a prototype and not a full sandbox, and should not be used to execute
+commands that you don't already trust on your system, (i.e. devices in `/dev` are
+mounted in the sandbox, and network calls are all allowed.) Please do not
+attempt any commands that will remove everything in /dev or write zeros to your
+disks.
+
 <img src="docs/try_pip_install_example.gif" alt="try gif">
 
 ## Getting Started