diff --git a/README.md b/README.md
index 3e9a948..fd61739 100644
--- a/README.md
+++ b/README.md
@@ -29,7 +29,11 @@ grunt.loadNpmTasks('grunt-ruby-haml');
 
 ## Documentation
 
-You'll need to install `grunt-ruby-haml`:
+Make sure you have underscore installed:
+
+    npm install underscore
+    
+Then you'll need to install `grunt-ruby-haml`:
 
     npm install grunt-ruby-haml