diff --git a/.rubocop.yml b/.rubocop.yml
index abd6e6a..630a477 100644
--- a/.rubocop.yml
+++ b/.rubocop.yml
@@ -1,6 +1,11 @@
 inherit_gem:
   jekyll: .rubocop.yml
 
+AllCops:
+  TargetRubyVersion: 2.3
+  Exclude:
+    - vendor/**/*
+
 Metrics/LineLength:
   Exclude:
     - spec/**/*
@@ -13,8 +18,3 @@ Metrics/BlockLength:
 Layout/IndentHeredoc:
   Exclude:
     - spec/**/*
-
-AllCops:
-  TargetRubyVersion: 2.1
-  Exclude:
-    - vendor/**/*
diff --git a/.travis.yml b/.travis.yml
index 9c2e01e..4c96096 100644
--- a/.travis.yml
+++ b/.travis.yml
@@ -1,6 +1,4 @@
 rvm:
-  - 2.1
-  - 2.2
   - 2.3
   - 2.4
   - 2.5
diff --git a/jekyll-seo-tag.gemspec b/jekyll-seo-tag.gemspec
index 7d1529c..19496a2 100644
--- a/jekyll-seo-tag.gemspec
+++ b/jekyll-seo-tag.gemspec
@@ -21,6 +21,8 @@ Gem::Specification.new do |spec|
     raise "RubyGems 2.0 or newer is required to protect against public gem pushes."
   end
 
+  spec.required_ruby_version = ">= 2.3.0"
+
   spec.files         = `git ls-files -z`.split("\x0").reject { |f| f.match(%r!^(test|spec|features)/!) }
   spec.bindir        = "exe"
   spec.executables   = spec.files.grep(%r!^exe/!) { |f| File.basename(f) }
@@ -30,5 +32,5 @@ Gem::Specification.new do |spec|
   spec.add_development_dependency "bundler", "~> 1.15"
   spec.add_development_dependency "html-proofer", "~> 3.7"
   spec.add_development_dependency "rspec", "~> 3.5"
-  spec.add_development_dependency "rubocop", "0.51"
+  spec.add_development_dependency "rubocop", "~> 0.56.0"
 end
diff --git a/lib/jekyll-seo-tag/drop.rb b/lib/jekyll-seo-tag/drop.rb
index 9b47166..b684229 100644
--- a/lib/jekyll-seo-tag/drop.rb
+++ b/lib/jekyll-seo-tag/drop.rb
@@ -5,7 +5,7 @@ module Jekyll
     class Drop < Jekyll::Drops::Drop
       include Jekyll::SeoTag::UrlHelper
 
-      TITLE_SEPARATOR = " | ".freeze
+      TITLE_SEPARATOR = " | "
       FORMAT_STRING_METHODS = %i[
         markdownify strip_html normalize_whitespace escape_once
       ].freeze
diff --git a/lib/jekyll-seo-tag/version.rb b/lib/jekyll-seo-tag/version.rb
index ed89abd..118fcb4 100644
--- a/lib/jekyll-seo-tag/version.rb
+++ b/lib/jekyll-seo-tag/version.rb
@@ -5,6 +5,6 @@ module Liquid; class Tag; end; end
 
 module Jekyll
   class SeoTag < Liquid::Tag
-    VERSION = "2.4.0".freeze
+    VERSION = "2.4.0"
   end
 end