diff --git a/.github/workflows/ci.yml b/.github/workflows/ci.yml
new file mode 100644
index 0000000..42b69f5
--- /dev/null
+++ b/.github/workflows/ci.yml
@@ -0,0 +1,60 @@
+name: Continuous Integration
+
+on:
+  push:
+    branches:
+    - master
+  pull_request:
+    branches:
+    - master
+
+jobs:
+  ci:
+    if: "!contains(github.event.commits[0].message, '[ci skip]')"
+    name: 'Ruby ${{ matrix.ruby_version }}'
+    runs-on: 'ubuntu-latest'
+
+    strategy:
+      fail-fast: false
+      matrix:
+        ruby_version:
+        - "2.7"
+        - "3.0"
+        - "3.3"
+    steps:
+      - uses: actions/checkout@v4
+        with:
+          fetch-depth: 5
+      - name: "Set up Ruby ${{ matrix.ruby_version }}"
+        uses: ruby/setup-ruby@v1
+        with:
+          ruby-version: ${{ matrix.ruby_version }}
+          bundler-cache: true
+      - name: Execute tests
+        run:  bash script/test
+      - name: Check Style Offenses
+        run:  bash script/fmt
+      - name: Test gem build
+        run:  bundle exec gem build jekyll-redirect-from.gemspec
+      - name: Test gem install
+        run:  bundle exec gem install jekyll-redirect-from --local --verbose
+
+  ghp:
+    if: "!contains(github.event.commits[0].message, '[ci skip]')"
+    name: Ruby 3.3 with GitHub Pages Gem
+    runs-on: 'ubuntu-latest'
+    env:
+      GH_PAGES: true
+    strategy:
+      fail-fast: false
+    steps:
+      - uses: actions/checkout@v4
+        with:
+          fetch-depth: 5
+      - name: "Set up Ruby 3.3"
+        uses: ruby/setup-ruby@v1
+        with:
+          ruby-version: 3.3
+          bundler-cache: true
+      - name: Execute tests
+        run:  bash script/test
diff --git a/.gitignore b/.gitignore
index 98dcaca..e47808f 100644
--- a/.gitignore
+++ b/.gitignore
@@ -13,6 +13,8 @@ pkg
 rdoc
 spec/reports
 spec/fixtures/.jekyll-metadata
+spec/fixtures/.jekyll-cache
 test/tmp
 test/version_tmp
 tmp
+vendor/bundle
diff --git a/.rubocop.yml b/.rubocop.yml
index 6d673b2..64db333 100644
--- a/.rubocop.yml
+++ b/.rubocop.yml
@@ -1,14 +1,41 @@
+inherit_from: .rubocop_todo.yml
+
+require: rubocop-jekyll
+
 inherit_gem:
-  jekyll: .rubocop.yml
+  rubocop-jekyll: .rubocop.yml
 
 AllCops:
+  TargetRubyVersion: 2.5
+  SuggestExtensions: false
   Exclude:
     - vendor/**/*
 
-Metrics/BlockLength:
+Layout/LineEndStringConcatenationIndentation:
+  Enabled: true
+
+Lint/EmptyInPattern:
+  Enabled: false
+
+Naming/InclusiveLanguage:
+  Enabled: false
+Naming/MemoizedInstanceVariableName:
   Exclude:
-    - spec/**/*
+    - 'lib/jekyll-redirect-from/page_without_a_file.rb'
+
+Performance/MapCompact:
+  Enabled: true
+Performance/RedundantEqualityComparisonBlock:
+  Enabled: true
+Performance/RedundantSplitRegexpArgument:
+  Enabled: true
 
-Metrics/LineLength:
+Style/ConcatArrayLiterals:
   Exclude:
-    - spec/**/*
+    - 'jekyll-redirect-from.gemspec'
+Style/InPatternThen:
+  Enabled: false
+Style/MultilineInPatternThen:
+  Enabled: false
+Style/QuotedSymbols:
+  Enabled: true
diff --git a/.rubocop_todo.yml b/.rubocop_todo.yml
new file mode 100644
index 0000000..b870d5e
--- /dev/null
+++ b/.rubocop_todo.yml
@@ -0,0 +1,27 @@
+# This configuration was generated by
+# `rubocop --auto-gen-config`
+# on 2021-09-17 12:49:45 UTC using RuboCop version 1.18.4.
+# The point is for the user to remove these configuration records
+# one by one as the offenses are removed from the code base.
+# Note that changes in the inspected code, or installation of new
+# versions of RuboCop, may require this file to be generated again.
+
+# Offense count: 3
+# Cop supports --auto-correct.
+# Configuration parameters: AutoCorrect, AllowHeredoc, AllowURI, URISchemes, IgnoreCopDirectives, IgnoredPatterns.
+# URISchemes: http, https
+Layout/LineLength:
+  Max: 105
+
+# Offense count: 2
+# Configuration parameters: AllowedMethods.
+# AllowedMethods: enums
+Lint/ConstantDefinitionInBlock:
+  Exclude:
+    - 'spec/jekyll_redirect_from/generator_spec.rb'
+
+# Offense count: 2
+# Configuration parameters: AllowComments, AllowEmptyLambdas.
+Lint/EmptyBlock:
+  Exclude:
+    - 'spec/jekyll_redirect_from/generator_spec.rb'
diff --git a/.travis.yml b/.travis.yml
deleted file mode 100644
index aba38c0..0000000
--- a/.travis.yml
+++ /dev/null
@@ -1,17 +0,0 @@
-language: ruby
-before_script: bundle update
-script: "script/cibuild"
-sudo: false
-cache: bundler
-
-matrix:
-  include:
-    - # GitHub Pages
-      rvm: 2.4.0
-      env: GH_PAGES=true
-
-rvm:
-  - 2.4
-  - 2.3
-  - 2.2
-  - 2.1
diff --git a/Gemfile b/Gemfile
index 668785f..661fc4f 100644
--- a/Gemfile
+++ b/Gemfile
@@ -1,6 +1,8 @@
+# frozen_string_literal: true
+
 source "https://rubygems.org"
 gemspec
 
-if ENV["GH_PAGES"]
-  gem "github-pages"
-end
+gem "github-pages" if ENV["GH_PAGES"]
+gem "jekyll", ENV["JEKYLL_VERSION"] if ENV["JEKYLL_VERSION"]
+gem "kramdown-parser-gfm" if ENV["JEKYLL_VERSION"] == "~> 3.9"
diff --git a/History.markdown b/History.markdown
index 5001743..5926bd5 100644
--- a/History.markdown
+++ b/History.markdown
@@ -1,11 +1,72 @@
 ## HEAD
 
+### styles
+
+  * style: Style/SpecialGlobalVars (#216)
+
+### Development Fixes
+
+  * fix Gemfile to correctly install jekyll 3.9 (#224)
+  * Refactor specs for RedirectPage (#222)
+  * Lock to RuboCop v1.18.x (#242)
+  * Clean up gemspec (#243)
+  * Bump versions in CI workflow (#273)
+
+### Bug Fixes
+
+  * Refactor Redirectable mixin to reduce allocations (#241)
+
+## 0.16.0 / 2020-01-26
+
+### Minor Enhancements
+
+  * Allows generation of `redirects.json` to be disabled (#207)
+  * Allow redirects from and for subclasses of page and document (#204)
+
+### Bug Fixes
+
+  * Use `Hash#key?` instead of `Hash#keys.any?` (#201)
+
+### Development Fixes
+
+  * Target Ruby 2.4
+  * Stop testing with backwards-compatible site config (#211)
+
+### Documentation
+
+  * Simplifies YAML for `redirect_to` (#185)
+
+## 0.15.0 / 2019-03-23
+
+### Development Fixes
+
+  * chore(deps): rubocop-jekyll 0.3 (#187)
+
+### Bug Fixes
+
+  * Allow testing and using with Jekyll 4.x (#196)
+
+## 0.14.0 / 2018-06-29
+
+### Minor Enhancements
+
+  * Run javascript at first to avoid splash (#158)
+
+### Development Fixes
+
+  * Use Rubocop 0.57
+  * Target Ruby 2.3
+  * Test against Ruby 2.5 (#173)
+
+## 0.13.0 / 2017-12-03
+
   * Test against same version of Ruby that GitHub Pages uses (#132)
 
 ### Development Fixes
 
   * Rubocop (#141)
   * Fix tests for jekyll 3.5.x (#160)
+  * Rubocop: autocorrect (#165)
 
 ### Minor Enhancements
 
@@ -17,6 +78,10 @@
 
   * Create redirects.json file (#147)
 
+### Documentation
+
+  * Update README.md (#167)
+
 ## 0.12.1 / 2017-01-12
 
 ### Development Fixes
diff --git a/LICENSE.txt b/LICENSE.txt
index 9830ee4..0295617 100644
--- a/LICENSE.txt
+++ b/LICENSE.txt
@@ -1,4 +1,4 @@
-Copyright (c) 2013 Parker Moore
+Copyright (c) 2013-present Parker Moore and jekyll-redirect-from contributors
 
 MIT License
 
diff --git a/README.md b/README.md
index 7e67460..ba340d5 100644
--- a/README.md
+++ b/README.md
@@ -9,7 +9,7 @@ impractical to create new pages in the proper subdirectories so they, e.g.
 Instead of dealing with maintaining those pages for redirection, let
 `jekyll-redirect-from` handle it for you.
 
-[![Build Status](https://travis-ci.org/jekyll/jekyll-redirect-from.svg?branch=master)](https://travis-ci.org/jekyll/jekyll-redirect-from)
+[![Build Status](https://github.com/jekyll/jekyll-redirect-from/actions/workflows/ci.yml/badge.svg?branch=master)](https://github.com/jekyll/jekyll-redirect-from/actions/workflows/ci.yml)
 
 ## How it Works
 
@@ -31,13 +31,15 @@ Or install it yourself as:
 
     $ gem install jekyll-redirect-from
 
-Once it's installed into your evironment, add it to your `_config.yml`:
+Once it's installed into your environment, add it to your `_config.yml`:
 
 ```yaml
-gems:
+plugins:
   - jekyll-redirect-from
 ```
 
+💡 If you are using a Jekyll version less than 3.5.0, use the `gems` key instead of `plugins`.
+
 If you're using Jekyll in `safe` mode to mimic GitHub Pages, make sure to
 add jekyll-redirect-from to your whitelist:
 
@@ -50,7 +52,7 @@ Then run `jekyll <cmd> --safe` like normal.
 
 ## Usage
 
-The object of this gem is to allow an author to specify multiple URLs for a
+The objective of this gem is to allow an author to specify multiple URLs for a
 page, such that the alternative URLs redirect to the new Jekyll URL.
 
 To use it, simply add the array to the YAML front-matter of your page or post:
@@ -66,7 +68,7 @@ Redirects including a trailing slash will generate a corresponding subdirectory
 
 For example...
 
-```text
+```yaml
 redirect_from:
   - /post/123456789/my-amazing-post
 ```
@@ -79,7 +81,7 @@ redirect_from:
 
 While...
 
-```text
+```yaml
 redirect_from:
   - /post/123456789/my-amazing-post/
 ```
@@ -94,7 +96,7 @@ These pages will contain an HTTP-REFRESH meta tag which redirect to your URL.
 
 You can also specify just **one url** like this:
 
-```text
+```yaml
 title: My other awesome post
 redirect_from: /post/123456798/
 ```
@@ -111,13 +113,9 @@ Sometimes, you may want to redirect a site page to a totally different website.
 
 ```yaml
 title: My amazing post
-redirect_to:
-  - http://www.github.com
+redirect_to: http://www.github.com
 ```
 
-If you have multiple `redirect_to`s set, only the first one will be respected.
-
-
 **Note**: Using `redirect_to` or `redirect_from` with collections will only work with files which are output to HTML, such as `.md`, `.textile`, `.html` etc.
 
 ## Customizing the redirect template
@@ -129,6 +127,19 @@ Your layout will get the following variables:
 * `page.redirect.from` - the relative path to the redirect page
 * `page.redirect.to` - the absolute URL (where available) to the target page
 
+## Configuration
+
+You can configure this plugin in `_config.yml` by adding to the `redirect_from` key.
+
+### Disabling `redirects.json`
+
+By default, a file called `redirects.json`, which can be used for automated testing or to implement server-side redirects, will be included in the output. To exclude it from the output, set the `json` key to `false`:
+
+```yml
+redirect_from:
+  json: false
+```
+
 ## Contributing
 
 1. Fork it
diff --git a/Rakefile b/Rakefile
index b7e9ed5..ee617bb 100644
--- a/Rakefile
+++ b/Rakefile
@@ -1,3 +1,5 @@
+# frozen_string_literal: true
+
 require "bundler/gem_tasks"
 require "rspec/core/rake_task"
 
diff --git a/jekyll-redirect-from.gemspec b/jekyll-redirect-from.gemspec
index ed00a1b..713ef0b 100644
--- a/jekyll-redirect-from.gemspec
+++ b/jekyll-redirect-from.gemspec
@@ -1,31 +1,26 @@
-# coding: utf-8
+# frozen_string_literal: true
 
-lib = File.expand_path("lib", __dir__)
-$LOAD_PATH.unshift(lib) unless $LOAD_PATH.include?(lib)
-require "jekyll-redirect-from/version"
+require_relative "lib/jekyll-redirect-from/version"
 
 Gem::Specification.new do |spec|
   spec.name          = "jekyll-redirect-from"
   spec.version       = JekyllRedirectFrom::VERSION
   spec.authors       = ["Parker Moore"]
   spec.email         = ["parkrmoore@gmail.com"]
-  spec.summary       = "Seamlessly specify multiple redirection URLs " \
-                       "for your pages and posts"
+  spec.summary       = "Seamlessly specify multiple redirection URLs for your pages and posts"
   spec.homepage      = "https://github.com/jekyll/jekyll-redirect-from"
   spec.license       = "MIT"
 
-  # rubocop:disable Style/SpecialGlobalVars
-  spec.files         = `git ls-files`.split($/)
-  # rubocop:enable Style/SpecialGlobalVars
-
-  spec.executables   = spec.files.grep(%r!^bin/!) { |f| File.basename(f) }
-  spec.test_files    = spec.files.grep(%r!^(test|spec|features)/!)
+  spec.files         = `git ls-files lib`.split("\n").concat(%w(LICENSE.txt README.md History.markdown))
   spec.require_paths = ["lib"]
 
-  spec.add_runtime_dependency "jekyll", "~> 3.3"
-  spec.add_development_dependency "bundler", "~> 1.3"
-  spec.add_development_dependency "rspec", "~> 3.5"
-  spec.add_development_dependency "rake", "~> 12.0"
+  spec.required_ruby_version = ">= 2.5.0"
+
+  spec.add_runtime_dependency "jekyll", ">= 3.3", "< 5.0"
+
+  spec.add_development_dependency "bundler"
   spec.add_development_dependency "jekyll-sitemap", "~> 1.0"
-  spec.add_development_dependency "rubocop", "~> 0.43"
+  spec.add_development_dependency "rake", "~> 13.0"
+  spec.add_development_dependency "rspec", "~> 3.5"
+  spec.add_development_dependency "rubocop-jekyll", "~> 0.13.0"
 end
diff --git a/lib/jekyll-redirect-from.rb b/lib/jekyll-redirect-from.rb
index 8e2a0aa..1922bc1 100644
--- a/lib/jekyll-redirect-from.rb
+++ b/lib/jekyll-redirect-from.rb
@@ -1,3 +1,5 @@
+# frozen_string_literal: true
+
 require "jekyll"
 require "jekyll-redirect-from/version"
 require "jekyll-redirect-from/generator"
diff --git a/lib/jekyll-redirect-from/context.rb b/lib/jekyll-redirect-from/context.rb
index 4f7de76..25cfcf9 100644
--- a/lib/jekyll-redirect-from/context.rb
+++ b/lib/jekyll-redirect-from/context.rb
@@ -1,3 +1,5 @@
+# frozen_string_literal: true
+
 module JekyllRedirectFrom
   # Stubbed LiquidContext to support relative_url and absolute_url helpers
   class Context
diff --git a/lib/jekyll-redirect-from/generator.rb b/lib/jekyll-redirect-from/generator.rb
index a93560d..52e68f5 100644
--- a/lib/jekyll-redirect-from/generator.rb
+++ b/lib/jekyll-redirect-from/generator.rb
@@ -1,3 +1,5 @@
+# frozen_string_literal: true
+
 module JekyllRedirectFrom
   class Generator < Jekyll::Generator
     safe true
@@ -8,18 +10,19 @@ def generate(site)
       @redirects = {}
 
       # Inject our layout, unless the user has already specified a redirect layout'
-      unless site.layouts.keys.any? { |name| name == "redirect" }
+      unless site.layouts.key?("redirect")
         site.layouts["redirect"] = JekyllRedirectFrom::Layout.new(site)
       end
 
       # Must duplicate pages to modify while in loop
       (site.docs_to_write + site.pages.dup).each do |doc|
-        next unless JekyllRedirectFrom::CLASSES.include?(doc.class)
+        next unless redirectable_document?(doc)
+
         generate_redirect_from(doc)
         generate_redirect_to(doc)
       end
 
-      generate_redirects_json
+      generate_redirects_json if generate_redirects_json?
     end
 
     private
@@ -35,6 +38,7 @@ def generate_redirect_from(doc)
 
     def generate_redirect_to(doc)
       return unless doc.redirect_to
+
       page = RedirectPage.redirect_to(doc, doc.redirect_to)
       doc.data.merge!(page.data)
       doc.content = doc.output = page.output
@@ -43,10 +47,19 @@ def generate_redirect_to(doc)
 
     def generate_redirects_json
       return if File.exist? site.in_source_dir("redirects.json")
+
       page = PageWithoutAFile.new(site, "", "", "redirects.json")
       page.content = redirects.to_json
       page.data["layout"] = nil
       site.pages << page
     end
+
+    def redirectable_document?(doc)
+      doc.is_a?(Jekyll::Document) || doc.is_a?(Jekyll::Page)
+    end
+
+    def generate_redirects_json?
+      site.config.dig("redirect_from", "json") != false
+    end
   end
 end
diff --git a/lib/jekyll-redirect-from/layout.rb b/lib/jekyll-redirect-from/layout.rb
index 82ad1c0..b39ca9d 100644
--- a/lib/jekyll-redirect-from/layout.rb
+++ b/lib/jekyll-redirect-from/layout.rb
@@ -1,3 +1,5 @@
+# frozen_string_literal: true
+
 module JekyllRedirectFrom
   # A stubbed layout for our default redirect template
   # We cannot use the standard Layout class because of site.in_source_dir
diff --git a/lib/jekyll-redirect-from/page_without_a_file.rb b/lib/jekyll-redirect-from/page_without_a_file.rb
index dddf90e..9604cb8 100644
--- a/lib/jekyll-redirect-from/page_without_a_file.rb
+++ b/lib/jekyll-redirect-from/page_without_a_file.rb
@@ -1,3 +1,5 @@
+# frozen_string_literal: true
+
 module JekyllRedirectFrom
   class PageWithoutAFile < Jekyll::Page
     def read_yaml(*)
diff --git a/lib/jekyll-redirect-from/redirect.html b/lib/jekyll-redirect-from/redirect.html
index 54ed750..6640310 100644
--- a/lib/jekyll-redirect-from/redirect.html
+++ b/lib/jekyll-redirect-from/redirect.html
@@ -3,9 +3,9 @@
   <meta charset="utf-8">
   <title>Redirecting&hellip;</title>
   <link rel="canonical" href="{{ page.redirect.to }}">
+  <script>location="{{ page.redirect.to }}"</script>
   <meta http-equiv="refresh" content="0; url={{ page.redirect.to }}">
   <meta name="robots" content="noindex">
   <h1>Redirecting&hellip;</h1>
   <a href="{{ page.redirect.to }}">Click here if you are not redirected.</a>
-  <script>location="{{ page.redirect.to }}"</script>
 </html>
diff --git a/lib/jekyll-redirect-from/redirect_page.rb b/lib/jekyll-redirect-from/redirect_page.rb
index 0bf64a9..58d022c 100644
--- a/lib/jekyll-redirect-from/redirect_page.rb
+++ b/lib/jekyll-redirect-from/redirect_page.rb
@@ -1,4 +1,4 @@
-# Encoding: utf-8
+# frozen_string_literal: true
 
 module JekyllRedirectFrom
   # Specialty page which implements the redirect path logic
@@ -45,13 +45,13 @@ def read_yaml(_base, _name, _opts = {})
     def set_paths(from, to)
       @context ||= context
       from = ensure_leading_slash(from)
-      data.merge!({
+      data.merge!(
         "permalink" => from,
         "redirect"  => {
           "from" => from,
-          "to"   => to =~ %r!^https?://! ? to : absolute_url(to),
-        },
-      })
+          "to"   => %r!^https?://!.match?(to) ? to : absolute_url(to),
+        }
+      )
     end
 
     def redirect_from
diff --git a/lib/jekyll-redirect-from/redirectable.rb b/lib/jekyll-redirect-from/redirectable.rb
index f9dffd8..4512a03 100644
--- a/lib/jekyll-redirect-from/redirectable.rb
+++ b/lib/jekyll-redirect-from/redirectable.rb
@@ -1,3 +1,5 @@
+# frozen_string_literal: true
+
 module JekyllRedirectFrom
   # Module which can be mixed in to documents (and pages) to provide
   # redirect_to and redirect_from helpers
@@ -5,21 +7,15 @@ module Redirectable
     # Returns a string representing the relative path or URL
     # to which the document should be redirected
     def redirect_to
-      if to_liquid["redirect_to"].is_a?(Array)
-        to_liquid["redirect_to"].compact.first
-      else
-        to_liquid["redirect_to"]
-      end
+      meta_data = to_liquid["redirect_to"]
+      meta_data.is_a?(Array) ? meta_data.compact.first : meta_data
     end
 
     # Returns an array representing the relative paths to other
     # documents which should be redirected to this document
     def redirect_from
-      if to_liquid["redirect_from"].is_a?(Array)
-        to_liquid["redirect_from"].compact
-      else
-        [to_liquid["redirect_from"]].compact
-      end
+      meta_data = to_liquid["redirect_from"]
+      meta_data.is_a?(Array) ? meta_data.compact : [meta_data].compact
     end
   end
 end
diff --git a/lib/jekyll-redirect-from/version.rb b/lib/jekyll-redirect-from/version.rb
index 964cca0..56f5d47 100644
--- a/lib/jekyll-redirect-from/version.rb
+++ b/lib/jekyll-redirect-from/version.rb
@@ -1,3 +1,5 @@
+# frozen_string_literal: true
+
 module JekyllRedirectFrom
-  VERSION = "0.12.1".freeze
+  VERSION = "0.16.0"
 end
diff --git a/script/bootstrap b/script/bootstrap
index 02278d9..e3126bf 100755
--- a/script/bootstrap
+++ b/script/bootstrap
@@ -1,3 +1,4 @@
 #! /bin/bash
+set -e
 
-bundle install -j8
+bundle install -j8 || bundle install
diff --git a/script/cibuild b/script/cibuild
index 10ff25d..40589af 100755
--- a/script/cibuild
+++ b/script/cibuild
@@ -1,6 +1,6 @@
 #! /bin/bash
 set -e
 
-bundle exec rake spec
-bundle exec rubocop -S -D
-gem build jekyll-redirect-from.gemspec
+script/test
+script/fmt
+bundle exec rake build
diff --git a/script/fmt b/script/fmt
new file mode 100755
index 0000000..913591a
--- /dev/null
+++ b/script/fmt
@@ -0,0 +1,10 @@
+#!/bin/bash
+set -e
+
+echo "RuboCop $(bundle exec rubocop --version)"
+bundle exec rubocop -D -E $@
+success=$?
+if ((success != 0)); then
+   echo -e "\nTry running \`script/fmt -a\` to automatically fix errors"
+fi
+exit $success
diff --git a/script/release b/script/release
index fbddd87..6c9fcf2 100755
--- a/script/release
+++ b/script/release
@@ -1,3 +1,4 @@
 #! /bin/bash
 
+script/cibuild
 bundle exec rake release
diff --git a/spec/integrations_spec.rb b/spec/integrations_spec.rb
index 404eed5..cb6f53d 100644
--- a/spec/integrations_spec.rb
+++ b/spec/integrations_spec.rb
@@ -1,3 +1,5 @@
+# frozen_string_literal: true
+
 RSpec.describe "JekyllRedirectFrom integration tests" do
   before { site.process }
   let(:relative_path) { "" }
@@ -15,7 +17,7 @@
     end
 
     context "multiple redirect froms" do
-      %w(help contact let-there/be/light-he-said geepers/mccreepin).each do |redirect|
+      ["help", "contact", "let-there/be/light-he-said", "geepers/mccreepin"].each do |redirect|
         context "the #{redirect} redirect" do
           let(:relative_path) { "#{redirect}.html" }
 
diff --git a/spec/jekyll_redirect_from/context_spec.rb b/spec/jekyll_redirect_from/context_spec.rb
index bdf3e0d..b619d03 100644
--- a/spec/jekyll_redirect_from/context_spec.rb
+++ b/spec/jekyll_redirect_from/context_spec.rb
@@ -1,3 +1,5 @@
+# frozen_string_literal: true
+
 RSpec.describe JekyllRedirectFrom::Context do
   subject { described_class.new(site) }
 
diff --git a/spec/jekyll_redirect_from/generator_spec.rb b/spec/jekyll_redirect_from/generator_spec.rb
index 536efcc..5a7767b 100644
--- a/spec/jekyll_redirect_from/generator_spec.rb
+++ b/spec/jekyll_redirect_from/generator_spec.rb
@@ -1,3 +1,5 @@
+# frozen_string_literal: true
+
 RSpec.describe JekyllRedirectFrom::Generator do
   before(:each) do
     site.read
@@ -92,7 +94,7 @@
     let(:redirects) { JSON.parse(contents) }
     let(:domain) { "http://jekyllrb.com" }
 
-    it "creates the redirets file" do
+    it "creates the redirects file" do
       expect(path).to exist
     end
 
@@ -138,10 +140,32 @@
         FileUtils.rm_f source_path
       end
 
-      it "doesn't overwrite redirets.json" do
+      it "doesn't overwrite redirects.json" do
         expect(path).to exist
-        expect(redirects).to eql({ "foo" => "bar" })
+        expect(redirects).to eql("foo" => "bar")
+      end
+    end
+
+    context "when explicitly disabled" do
+      let(:site) { Jekyll::Site.new(config.merge("redirect_from" => { "json" => false })) }
+
+      it "does not create the redirects file" do
+        expect(path).to_not exist
       end
     end
   end
+
+  context "redirectable_document?" do
+    let(:generator) { JekyllRedirectFrom::Generator.new }
+
+    it "accepts subclasses of Jekyll::Document" do
+      SubclassOfJekyllDocument = Class.new(Jekyll::Document) { define_method(:initialize) {} }
+      expect(generator.send(:redirectable_document?, SubclassOfJekyllDocument.new)).to be_truthy
+    end
+
+    it "accepts subclasses of Jekyll::Page" do
+      SubclassOfJekyllPage = Class.new(Jekyll::Page) { define_method(:initialize) {} }
+      expect(generator.send(:redirectable_document?, SubclassOfJekyllPage.new)).to be_truthy
+    end
+  end
 end
diff --git a/spec/jekyll_redirect_from/layout_spec.rb b/spec/jekyll_redirect_from/layout_spec.rb
index 12a0748..60d6f42 100644
--- a/spec/jekyll_redirect_from/layout_spec.rb
+++ b/spec/jekyll_redirect_from/layout_spec.rb
@@ -1,3 +1,5 @@
+# frozen_string_literal: true
+
 RSpec.describe JekyllRedirectFrom::Layout do
   subject { described_class.new(@site) }
 
diff --git a/spec/jekyll_redirect_from/redirect_page_spec.rb b/spec/jekyll_redirect_from/redirect_page_spec.rb
index fefcc8d..b5af971 100644
--- a/spec/jekyll_redirect_from/redirect_page_spec.rb
+++ b/spec/jekyll_redirect_from/redirect_page_spec.rb
@@ -1,148 +1,142 @@
-# Encoding: utf-8
+# frozen_string_literal: true
 
 describe JekyllRedirectFrom::RedirectPage do
-  let(:from) { "/foo" }
-  let(:to) { "/bar" }
   let(:site_url) { site.config["url"] }
-  subject { described_class.from_paths(site, from, to) }
   before { site.read }
 
-  context "being a page" do
-    before { subject.read_yaml(nil, nil, nil) }
+  shared_examples "a redirect page" do
+    context "being a page" do
+      before { page.read_yaml(nil, nil, nil) }
 
-    it "returns no content" do
-      expect(subject.content).to eql("")
-    end
+      it "returns no content" do
+        expect(page.content).to eql("")
+      end
 
-    it "returns no output" do
-      expect(subject.output).to eql("")
-    end
+      it "returns no output" do
+        expect(page.output).to eql("")
+      end
 
-    it "sets default data" do
-      expect(subject.to_liquid["layout"]).to eql("redirect")
-      expect(subject.to_liquid["sitemap"]).to be_falsey
-    end
-  end
+      it "sets default data" do
+        expect(page.to_liquid["layout"]).to eql("redirect")
+        expect(page.to_liquid["sitemap"]).to be_falsey
+      end
 
-  context "creating a page from paths" do
-    it "sets the permalink" do
-      expect(subject.to_liquid["permalink"]).to eql(from)
-    end
+      it "sets the paths" do
+        expect(page.to_liquid["permalink"]).to eql(from)
+        expect(page.to_liquid).to have_key("redirect")
+        expect(page.to_liquid["redirect"]["from"]).to eql(from)
+        expect(page.to_liquid["redirect"]["to"]).to eql("#{site_url}#{to}")
+      end
+
+      it "sets the permalink" do
+        expect(page.to_liquid["permalink"]).to eql(from)
+      end
 
-    it "sets redirect metadata" do
-      expect(subject.to_liquid).to have_key("redirect")
-      expect(subject.to_liquid["redirect"]["from"]).to eql(from)
-      expect(subject.to_liquid["redirect"]["to"]).to eql("#{site_url}#{to}")
+      it "sets redirect metadata" do
+        expect(page.to_liquid).to have_key("redirect")
+        expect(page.to_liquid["redirect"]["from"]).to eql(from)
+        expect(page.to_liquid["redirect"]["to"]).to eql("#{site_url}#{to}")
+      end
     end
 
-    context "with a document" do
-      let(:doc) { site.documents.first }
+    context "generating" do
+      before { site.generate }
+      let(:output) { Jekyll::Renderer.new(site, page, site.site_payload).run }
 
-      context "redirect from" do
-        let(:page) { described_class.redirect_from(doc, from) }
+      it "renders the template" do
+        expect(output).to_not be_nil
+        expect(output.to_s).to_not be_empty
+      end
 
-        it "creates with redirect_from" do
-          expect(page.to_liquid["permalink"]).to eql(from)
-          expect(page.to_liquid).to have_key("redirect")
-          expect(page.to_liquid["redirect"]["from"]).to eql(from)
-          expected = "http://jekyllrb.com/2014/01/03/redirect-me-plz.html"
-          expect(page.to_liquid["redirect"]["to"]).to eql(expected)
-        end
+      it "contains the meta refresh tag" do
+        expect(output).to match("<meta http-equiv=\"refresh\" content=\"0; url=#{site_url}#{to}\">")
       end
 
-      context "redirect to" do
-        let(:page) { described_class.redirect_to(doc, to) }
+      it "contains the javascript redirect" do
+        expect(output).to match("<script>location=\"#{site_url}#{to}\"</script>")
+      end
 
-        context "redirecting to a path" do
-          let(:to) { "/bar" }
+      it "contains canonical link in header" do
+        expect(output).to match("<link rel=\"canonical\" href=\"#{site_url}#{to}\">")
+      end
 
-          it "redirects" do
-            expect(page.to_liquid["permalink"]).to eql("/2014/01/03/redirect-me-plz.html")
-            expect(page.to_liquid).to have_key("redirect")
-            expect(page.to_liquid["redirect"]["to"]).to eql("#{site_url}#{to}")
-            expect(page.to_liquid["redirect"]["from"]).to eql("/2014/01/03/redirect-me-plz.html")
-          end
+      it "contains the clickable link" do
+        expect(output).to match("<a href=\"#{site_url}#{to}\">Click here if you are not redirected.</a>")
+      end
+    end
+  end
 
-          context "with no leading slash" do
-            let(:to) { "bar" }
+  context "redirecting to" do
+    let(:to) { "/bar" }
+    let(:doc) { site.documents.first }
+    subject(:page) { described_class.redirect_to(doc, to) }
+    let(:from) { doc.url }
 
-            it "redirects" do
-              expect(page.to_liquid).to have_key("redirect")
-              expect(page.to_liquid["redirect"]["to"]).to eql("#{site_url}/#{to}")
-            end
-          end
+    it_behaves_like "a redirect page"
 
-          context "with a trailing slash" do
-            let(:to) { "/bar/" }
+    context "a relative path" do
+      let(:to) { "/bar" }
 
-            it "redirects" do
-              expect(page.to_liquid).to have_key("redirect")
-              expect(page.to_liquid["redirect"]["to"]).to eql("#{site_url}#{to}")
-            end
-          end
-        end
+      it "redirects" do
+        expect(page.to_liquid["permalink"]).to eql("/2014/01/03/redirect-me-plz.html")
+        expect(page.to_liquid).to have_key("redirect")
+        expect(page.to_liquid["redirect"]["to"]).to eql("#{site_url}#{to}")
+        expect(page.to_liquid["redirect"]["from"]).to eql("/2014/01/03/redirect-me-plz.html")
+      end
 
-        context "redirecting to a URL" do
-          let(:to) { "https://foo.invalid" }
+      context "with no leading slash" do
+        let(:to) { "bar" }
 
-          it "redirects" do
-            expect(page.to_liquid["permalink"]).to eql("/2014/01/03/redirect-me-plz.html")
-            expect(page.to_liquid).to have_key("redirect")
-            expect(page.to_liquid["redirect"]["to"]).to eql("https://foo.invalid")
-            expect(page.to_liquid["redirect"]["from"]).to eql("/2014/01/03/redirect-me-plz.html")
-          end
+        it "redirects" do
+          expect(page.to_liquid).to have_key("redirect")
+          expect(page.to_liquid["redirect"]["to"]).to eql("#{site_url}/#{to}")
         end
       end
-    end
-  end
-
-  context "setting the paths" do
-    let(:from) { "/foo2" }
-    let(:to) { "/bar2" }
 
-    before { subject.set_paths(from, to) }
+      context "with a trailing slash" do
+        let(:to) { "/bar/" }
 
-    it "sets the paths" do
-      expect(subject.to_liquid["permalink"]).to eql(from)
-      expect(subject.to_liquid).to have_key("redirect")
-      expect(subject.to_liquid["redirect"]["from"]).to eql(from)
-      expect(subject.to_liquid["redirect"]["to"]).to eql("#{site_url}#{to}")
+        it "redirects" do
+          expect(page.to_liquid).to have_key("redirect")
+          expect(page.to_liquid["redirect"]["to"]).to eql("#{site_url}#{to}")
+        end
+      end
     end
-  end
-
-  context "generating" do
-    before { site.generate }
-    let(:output) { Jekyll::Renderer.new(site, subject, site.site_payload).run }
 
-    it "renders the template" do
-      expect(output).to_not be_nil
-      expect(output.to_s).to_not be_empty
-    end
+    context "an absolute URL" do
+      let(:to) { "https://foo.invalid" }
 
-    it "contains the meta refresh tag" do
-      expect(output).to match("<meta http-equiv=\"refresh\" content=\"0; url=#{site_url}#{to}\">")
+      it "redirects" do
+        expect(page.to_liquid["permalink"]).to eql("/2014/01/03/redirect-me-plz.html")
+        expect(page.to_liquid).to have_key("redirect")
+        expect(page.to_liquid["redirect"]["to"]).to eql("https://foo.invalid")
+        expect(page.to_liquid["redirect"]["from"]).to eql("/2014/01/03/redirect-me-plz.html")
+      end
     end
+  end
 
-    it "contains the javascript redirect" do
-      expect(output).to match("<script>location=\"#{site_url}#{to}\"</script>")
-    end
+  context "redirecting from" do
+    let(:from) { "/foo" }
+    let(:doc) { site.documents.first }
+    subject(:page) { described_class.redirect_from(doc, from) }
+    let(:to) { doc.url }
 
-    it "contains canonical link in header" do
-      expect(output).to match("<link rel=\"canonical\" href=\"#{site_url}#{to}\">")
-    end
+    it_behaves_like "a redirect page"
 
-    it "contains the clickable link" do
-      expect(output).to match("<a href=\"#{site_url}#{to}\">Click here if you are not redirected.</a>")
+    it "sets liquid data for the page" do
+      expect(page.to_liquid["permalink"]).to eql(from)
+      expect(page.to_liquid).to have_key("redirect")
+      expect(page.to_liquid["redirect"]["from"]).to eql(from)
+      expected = "http://jekyllrb.com/2014/01/03/redirect-me-plz.html"
+      expect(page.to_liquid["redirect"]["to"]).to eql(expected)
     end
-  end
 
-  context "redirect from destination" do
     context "when redirect from has no extension" do
       let(:from) { "/foo" }
 
       it "adds .html" do
         expected = File.expand_path "foo.html", site.dest
-        expect(subject.destination("/")).to eql(expected)
+        expect(page.destination("/")).to eql(expected)
       end
     end
 
@@ -151,7 +145,11 @@
 
       it "knows to add the index.html" do
         expected = File.expand_path "foo/index.html", site.dest
-        expect(subject.destination("/")).to eql(expected)
+        expect(page.destination("/")).to eql(expected)
+      end
+
+      it "uses HTML" do
+        expect(page.output_ext).to eql(".html")
       end
     end
 
@@ -160,7 +158,7 @@
 
       it "adds .html" do
         expected = File.expand_path "foo.html", site.dest
-        expect(subject.destination("/")).to eql(expected)
+        expect(page.destination("/")).to eql(expected)
       end
     end
 
@@ -169,7 +167,11 @@
 
       it "doesn't add .html" do
         expected = File.expand_path "foo.htm", site.dest
-        expect(subject.destination("/")).to eql(expected)
+        expect(page.destination("/")).to eql(expected)
+      end
+
+      it "honors the extension" do
+        expect(page.output_ext).to eql(".htm")
       end
     end
 
@@ -178,33 +180,11 @@
 
       it "adds the slash" do
         expected = File.expand_path "foo.html", site.dest
-        expect(subject.destination("/")).to eql(expected)
+        expect(page.destination("/")).to eql(expected)
       end
-    end
-  end
-
-  context "output extension" do
-    context "with an extension" do
-      let(:from) { "foo.htm" }
-
-      it "honors the extension" do
-        expect(subject.output_ext).to eql(".htm")
-      end
-    end
-
-    context "with a trailing slash" do
-      let(:from) { "foo/" }
-
-      it "uses HTML" do
-        expect(subject.output_ext).to eql(".html")
-      end
-    end
-
-    context "with no slash" do
-      let(:from) { "foo" }
 
       it "uses HTML" do
-        expect(subject.output_ext).to eql(".html")
+        expect(page.output_ext).to eql(".html")
       end
     end
   end
diff --git a/spec/jekyll_redirect_from/redirectable_spec.rb b/spec/jekyll_redirect_from/redirectable_spec.rb
index 09cfc92..c9a2108 100644
--- a/spec/jekyll_redirect_from/redirectable_spec.rb
+++ b/spec/jekyll_redirect_from/redirectable_spec.rb
@@ -1,3 +1,5 @@
+# frozen_string_literal: true
+
 class RedirectableTestHelper
   include JekyllRedirectFrom::Redirectable
   attr_reader :to_liquid
diff --git a/spec/spec_helper.rb b/spec/spec_helper.rb
index ca35d6d..c089254 100644
--- a/spec/spec_helper.rb
+++ b/spec/spec_helper.rb
@@ -1,3 +1,5 @@
+# frozen_string_literal: true
+
 require "jekyll"
 require File.expand_path("lib/jekyll-redirect-from.rb")
 
@@ -32,7 +34,7 @@ def dest_dir(*paths)
   end
 
   def config
-    Jekyll.configuration({
+    Jekyll.configuration(
       "source"      => fixtures_path.to_s,
       "destination" => fixtures_path.join("_site").to_s,
       "collections" => {
@@ -40,15 +42,12 @@ def config
         "authors"  => {},
       },
       "url"         => "http://jekyllrb.com",
-      "gems"        => [
-        "jekyll-redirect-from",
-        "jekyll-sitemap",
-      ],
+      "plugins"     => %w(jekyll-redirect-from jekyll-sitemap),
       "defaults"    => [{
         "scope"  => { "path" => "" },
         "values" => { "layout" => "layout" },
-      },],
-    }).backwards_compatibilize
+      }]
+    )
   end
 
   def site