diff --git a/Gemfile b/Gemfile
index 5fcd95e..96e5d5d 100644
--- a/Gemfile
+++ b/Gemfile
@@ -1,10 +1,15 @@
 source 'https://rubygems.org'
 
 gem 'yard'
-gem 'puppet', '~> 3.6.2'
 gem 'rgen'
 gem 'redcarpet'
 
+if puppetversion = ENV['PUPPET_VERSION']
+  gem 'puppet', puppetversion
+else
+  gem 'puppet', '~> 3.6.2'
+end
+
 group :test do
   gem 'rspec'
   gem 'mocha'