diff --git a/.rubocop.yml b/.rubocop.yml
index 53a2400..75704dd 100644
--- a/.rubocop.yml
+++ b/.rubocop.yml
@@ -5,12 +5,3 @@ AllCops:
   TargetRubyVersion: 2.3
   Exclude:
     - vendor/**/*
-
-Metrics/LineLength:
-  Exclude:
-    - spec/**/*
-    - jekyll-mentions.gemspec
-
-Metrics/BlockLength:
-  Exclude:
-    - spec/**/*
diff --git a/jekyll-mentions.gemspec b/jekyll-mentions.gemspec
index 1357d81..531abe8 100644
--- a/jekyll-mentions.gemspec
+++ b/jekyll-mentions.gemspec
@@ -21,5 +21,5 @@ Gem::Specification.new do |s|
 
   s.add_development_dependency "rake", "~> 12.0"
   s.add_development_dependency "rspec", "~> 3.0"
-  s.add_development_dependency "rubocop", "~> 0.57.2"
+  s.add_development_dependency "rubocop-jekyll", "~> 0.3"
 end
diff --git a/lib/jekyll-mentions.rb b/lib/jekyll-mentions.rb
index b8016d4..22553d8 100644
--- a/lib/jekyll-mentions.rb
+++ b/lib/jekyll-mentions.rb
@@ -8,7 +8,7 @@ class Mentions
     GITHUB_DOT_COM = "https://github.com"
     BODY_START_TAG = "<body"
 
-    OPENING_BODY_TAG_REGEX = %r!<body(.*?)>\s*!
+    OPENING_BODY_TAG_REGEX = %r!<body(.*?)>\s*!.freeze
 
     InvalidJekyllMentionConfig = Class.new(Jekyll::Errors::FatalException)
 
@@ -17,6 +17,7 @@ class << self
       def mentionify(doc)
         content = doc.output
         return unless content.include?("@")
+
         src = mention_base(doc.site.config)
         if content.include? BODY_START_TAG
           head, opener, tail  = content.partition(OPENING_BODY_TAG_REGEX)
@@ -28,6 +29,7 @@ def mentionify(doc)
           doc.output       = String.new(head) << opener << processed_markup << rest.join
         else
           return unless content =~ filter_regex
+
           doc.output = filter_with_mention(src).call(content)[:output].to_s
         end
       end
@@ -93,13 +95,14 @@ def mentionable?(doc)
       private
 
       def filter_regex
-        @filter_regex ||= begin
-          Regexp.new(
-            HTML::Pipeline::MentionFilter::MentionPatterns[mention_username_pattern]
-          )
-        rescue TypeError
-          %r!@\w+!
-        end
+        @filter_regex ||=
+          begin
+            Regexp.new(
+              HTML::Pipeline::MentionFilter::MentionPatterns[mention_username_pattern]
+            )
+          rescue TypeError
+            %r!@\w+!
+          end
       end
 
       def default_mention_base