diff --git a/README b/README
index e08cc5b..410201d 100644
--- a/README
+++ b/README
@@ -576,6 +576,10 @@ To run pupept rspec tests:
     bundle install --path vendor/bundle
     bundle exec rake spec
 
+Using different facter/puppet versions:
+
+    FACTER_GEM_VERSION=1.6.10 PUPPET_GEM_VERSION=2.7.23 bundle install --path vendor/bundle
+    bundle exec rake spec
 
 Licensing
 =========