diff --git a/README.md b/README.md
index f05602a..8ca2766 100644
--- a/README.md
+++ b/README.md
@@ -15,6 +15,7 @@ Lots of fun options!
 * `:force_run` kills any process that's holding open the listen port before attempting to (re)start Rails (default `false`).
 * `:daemon` runs the server as a daemon, without any output to the terminal that ran `guard` (default `false`).
 * `:timeout` waits this number of seconds when restarting the Rails server before reporting there's a problem (default `20`).
+* `:server` lets you specify the webserver engine to use (try `:server => :thin`).
 
 This is super-alpha, but it works for me! Only really hand-tested in Mac OS X. Feel free to fork'n'fix for other
 OSes, and to add some more real tests.