diff --git a/Gemfile b/Gemfile
index 4e68666..40cc71c 100644
--- a/Gemfile
+++ b/Gemfile
@@ -5,3 +5,4 @@ gem 'haml'
 gem 'data_mapper'
 gem 'dm-postgres-adapter'
 gem 'pg'
+gem 'petrify', git: 'https://github.com/adrianshort/petrify/'
diff --git a/Gemfile.lock b/Gemfile.lock
index 8278193..9d7d1b0 100644
--- a/Gemfile.lock
+++ b/Gemfile.lock
@@ -1,3 +1,10 @@
+GIT
+  remote: https://github.com/adrianshort/petrify/
+  revision: b1b04d7c3a7463e295d55703d5e2fa3288fa650a
+  specs:
+    petrify (0.2.0)
+      haml
+
 GEM
   remote: https://rubygems.org/
   specs:
@@ -75,6 +82,7 @@ DEPENDENCIES
   data_mapper
   dm-postgres-adapter
   haml
+  petrify!
   pg
 
 RUBY VERSION