diff --git a/.travis.yml b/.travis.yml
index 088fadae..c582e113 100644
--- a/.travis.yml
+++ b/.travis.yml
@@ -5,9 +5,10 @@ language: ruby
 sudo: false
 
 rvm:
-  - &ruby1 2.3.4
-  - &ruby2 2.2.7
-  - &ruby3 2.1.10
+  - &ruby1 2.4.0
+  - &ruby2 2.3.4
+  - &ruby3 2.2.7
+  - &ruby4 2.1.10
   - &jruby jruby-9.1.7.0
 
 matrix:
@@ -16,6 +17,10 @@ matrix:
       env: TEST_SUITE=fmt
     - rvm: *ruby1
       env: TEST_SUITE=default-site
+    - rvm: *ruby2
+      env: TEST_SUITE=fmt
+    - rvm: *ruby2
+      env: TEST_SUITE=default-site
   exclude:
     - rvm: *jruby
       env: TEST_SUITE=cucumber
@@ -49,3 +54,6 @@ addons:
 # regular test configuration
 after_success:
   - bundle exec codeclimate-test-reporter
+
+before_install:
+  - gem update --system
diff --git a/Gemfile b/Gemfile
index a310188f..928f1283 100644
--- a/Gemfile
+++ b/Gemfile
@@ -3,6 +3,8 @@ gemspec :name => "jekyll"
 
 gem "rake", "~> 12.0"
 
+gem "pygments.rb", "~> 1.1"
+
 # Dependency of jekyll-mentions. RubyGems in Ruby 2.1 doesn't shield us from this.
 gem "activesupport", "~> 4.2", :groups => [:test_legacy, :site] if RUBY_VERSION < "2.2.2"
 
@@ -75,7 +77,6 @@ group :jekyll_optional_dependencies do
   platform :ruby, :mswin, :mingw, :x64_mingw do
     gem "classifier-reborn", "~> 2.1.0"
     gem "liquid-c", "~> 3.0"
-    gem "pygments.rb", "~> 0.6.0"
     gem "rdiscount", "~> 2.0"
     gem "redcarpet", "~> 3.2", ">= 3.2.3"
   end