diff --git a/CONTRIBUTING.md b/CONTRIBUTING.md
index 8d6d1a3d15..af1b9b54c2 100644
--- a/CONTRIBUTING.md
+++ b/CONTRIBUTING.md
@@ -9,6 +9,8 @@ This document describes development setup and pointers for diving into this proj
 $ git clone https://github.com/ruby/ruby.wasm
 $ cd ruby.wasm
 $ ./bin/setup
+# Compile extension library
+$ bundle exec rake compile
 $ rake --tasks
 ```