diff --git a/docker.sh b/docker.sh
index 4d7925b..30c9fc0 100755
--- a/docker.sh
+++ b/docker.sh
@@ -1,5 +1,7 @@
 #! /usr/bin/env sh
 
+## Run this from inside the `i2p.plugins.firefox` checkout.
+
 docker build -t eyedeekay/i2p.plugins.firefox .
 xhost + local:docker
 docker run -it --rm \