diff --git a/.travis.yml b/.travis.yml
index e158f8c..e0c46a9 100644
--- a/.travis.yml
+++ b/.travis.yml
@@ -1,8 +1,11 @@
 language: ruby
 rvm:
-- 2.3.0
+- 2.5
+- 2.4
+- 2.3
 - 2.2
-- 2.1
+before_install: 
+- gem update --system
 script: script/cibuild
 sudo: false
 cache: bundler
diff --git a/jekyll-mentions.gemspec b/jekyll-mentions.gemspec
index 6a8b809..2fc9bd3 100644
--- a/jekyll-mentions.gemspec
+++ b/jekyll-mentions.gemspec
@@ -16,5 +16,5 @@ Gem::Specification.new do |s|
   s.add_dependency "jekyll", "~> 3.0"
 
   s.add_development_dependency "rspec", "~> 3.0"
-  s.add_development_dependency "rubocop", "~> 0.48"
+  s.add_development_dependency "rubocop", "0.51"
 end