diff --git a/.travis.yml b/.travis.yml
index 3df59731..d917e813 100644
--- a/.travis.yml
+++ b/.travis.yml
@@ -2,6 +2,7 @@ cache: bundler
 sudo: false
 language: ruby
 rvm:
+  - 2.0
   - 2.2.3
   - jruby-head
 
diff --git a/closure_tree.gemspec b/closure_tree.gemspec
index b0e95954..ff90f8c8 100644
--- a/closure_tree.gemspec
+++ b/closure_tree.gemspec
@@ -14,7 +14,7 @@ Gem::Specification.new do |gem|
 
   gem.files       = `git ls-files`.split($INPUT_RECORD_SEPARATOR)
   gem.test_files  = gem.files.grep(%r{^spec/})
-  gem.required_ruby_version = '>= 2.1.0'
+  gem.required_ruby_version = '>= 2.0.0'
 
   gem.add_runtime_dependency 'activerecord', '>= 4.1.0'
   gem.add_runtime_dependency 'with_advisory_lock', '>= 3.0.0'