diff --git a/.travis.yml b/.travis.yml
index 489846c..bfed563 100644
--- a/.travis.yml
+++ b/.travis.yml
@@ -1,12 +1,12 @@
 language: ruby
-sudo: false
 cache: bundler
 script:
-- bundle exec rake spec
+  - bundle exec rake spec
 rvm:
-- 1.9.3
-- 2.0.0
-- 2.1.5
+  - "2.1"
+  - "2.4"
+  - "2.5"
+  - "2.6"
 matrix:
   fast_finish: true
 deploy:
@@ -14,7 +14,7 @@ deploy:
   api_key:
     secure: "QpxxVQ8+0af/LVbFtZRYlJcY431xX7VTqPT7jjwO3x0PV3MLJcH+baGvoxAceAEbD0xgHPQGiFxSNhAZIwDBg9hW28ADP089HO0yxPxY/G7hBdLU9ZpSVe14p2V2M30SKcJ+vmNugK4oq26/ebe5NmoUCALClwyjZMNCXHr8OoQ="
   on:
-    rvm: 2.1.5
+    rvm: "2.6"
     tags: true
     all_branches: true
 notifications:
diff --git a/puppet-lint-absolute_classname-check.gemspec b/puppet-lint-absolute_classname-check.gemspec
index 590b9a1..c16aa8f 100644
--- a/puppet-lint-absolute_classname-check.gemspec
+++ b/puppet-lint-absolute_classname-check.gemspec
@@ -17,6 +17,8 @@ Gem::Specification.new do |spec|
     A puppet-lint plugin to check that classes are included by their absolute name.
   EOF
 
+  spec.required_ruby_version = '>= 2.1.0'
+
   spec.add_dependency             'puppet-lint', '>= 1.0', '< 3.0'
   spec.add_development_dependency 'coveralls'
   spec.add_development_dependency 'mime-types'