add notes on install protoc
diff --git a/README.md b/README.md
index 79f6eb3..2344809 100644
--- a/README.md
+++ b/README.md
@@ -109,6 +109,11 @@
 Hacking
 -------
 
+You need to have `protoc` installed.
+
+* Linux Aptitude: `apt-get install protobuf-compiler`
+* Mac [homebrew](http://brew.sh/): `brew install protobuf`
+
 Remember to run the tests. That is as easy as `make run-tests`.
 
 The default way of running the Dart protoc plugin is through the