diff --git a/.rubocop.yml b/.rubocop.yml
index c87f541..5a712a8 100644
--- a/.rubocop.yml
+++ b/.rubocop.yml
@@ -4,5 +4,5 @@ Metrics/LineLength:
   Enabled: false
 
 #http://viget.com/extend/just-use-double-quoted-ruby-strings
-#Style/StringLiterals:
-#  EnforcedStyle: double_quotes
+Style/StringLiterals:
+  EnforcedStyle: double_quotes
diff --git a/Gemfile b/Gemfile
index efdc678..81abda6 100644
--- a/Gemfile
+++ b/Gemfile
@@ -1,14 +1,14 @@
-source 'https://rubygems.org'
+source "https://rubygems.org"
 
-gem 'rake'
+gem "rake"
 
-gem 'github_api'
-gem 'colorize'
+gem "github_api"
+gem "colorize"
 
 group :test do
-  gem 'rspec'
-  gem 'rubocop'
-  gem 'coveralls', require: false
-  gem 'simplecov', require: false
-  gem 'codeclimate-test-reporter'
+  gem "rspec"
+  gem "rubocop"
+  gem "coveralls", require: false
+  gem "simplecov", require: false
+  gem "codeclimate-test-reporter"
 end
diff --git a/Rakefile b/Rakefile
index 3cc4800..4254421 100644
--- a/Rakefile
+++ b/Rakefile
@@ -1,5 +1,5 @@
-require 'rubocop/rake_task'
-require 'rspec/core/rake_task'
+require "rubocop/rake_task"
+require "rspec/core/rake_task"
 
 RuboCop::RakeTask.new
 RSpec::Core::RakeTask.new(:rspec)
diff --git a/bin/github_changelog_generator b/bin/github_changelog_generator
index f7c751f..f0c5fd4 100755
--- a/bin/github_changelog_generator
+++ b/bin/github_changelog_generator
@@ -1,4 +1,4 @@
 #! /usr/bin/env ruby
 
-require_relative '../lib/github_changelog_generator'
+require_relative "../lib/github_changelog_generator"
 GitHubChangelogGenerator::ChangelogGenerator.new.compound_changelog
diff --git a/bump_gemfile.rb b/bump_gemfile.rb
index 8847817..4401616 100755
--- a/bump_gemfile.rb
+++ b/bump_gemfile.rb
@@ -1,7 +1,7 @@
 #!/usr/bin/env ruby
-require 'optparse'
+require "optparse"
 
-SPEC_TYPE = 'gemspec'
+SPEC_TYPE = "gemspec"
 
 :major
 :minor
@@ -10,21 +10,21 @@ SPEC_TYPE = 'gemspec'
 @options = { dry_run: false, bump_number: :patch }
 
 OptionParser.new { |opts|
-  opts.banner = 'Usage: bump.rb [options]'
+  opts.banner = "Usage: bump.rb [options]"
 
-  opts.on('-d', '--dry-run', 'Dry run') do |v|
+  opts.on("-d", "--dry-run", "Dry run") do |v|
     @options[:dry_run] = v
   end
-  opts.on('-a', '--major', 'Bump major version') do |_v|
+  opts.on("-a", "--major", "Bump major version") do |_v|
     @options[:bump_number] = :major
   end
-  opts.on('-m', '--minor', 'Bump minor version') do |_v|
+  opts.on("-m", "--minor", "Bump minor version") do |_v|
     @options[:bump_number] = :minor
   end
-  opts.on('-p', '--patch', 'Bump patch version') do |_v|
+  opts.on("-p", "--patch", "Bump patch version") do |_v|
     @options[:bump_number] = :patch
   end
-  opts.on('-r', '--revert', 'Revert last bump') do |v|
+  opts.on("-r", "--revert", "Revert last bump") do |v|
     @options[:revert] = v
   end
 }.parse!
@@ -32,15 +32,15 @@ OptionParser.new { |opts|
 p @options
 
 def check_repo_is_clean_or_dry_run
-  value = `#{'git status --porcelain'}`
+  value = `#{"git status --porcelain"}`
 
   if value.empty?
-    puts 'Repo is clean -> continue'
+    puts "Repo is clean -> continue"
   else
     if @options[:dry_run]
       puts 'Repo not clean, "Dry run" enabled -> continue'
     else
-      puts 'Repository not clean -> exit'
+      puts "Repository not clean -> exit"
       exit
     end
   end
@@ -50,7 +50,7 @@ def find_spec_file
   list_of_specs = execute_line("find . -name '*.#{SPEC_TYPE}'")
   arr = list_of_specs.split("\n")
 
-  spec_file = ''
+  spec_file = ""
 
   case arr.count
     when 0
@@ -59,7 +59,7 @@ def find_spec_file
     when 1
       spec_file = arr[0]
     else
-      puts 'Which spec should be used?'
+      puts "Which spec should be used?"
       arr.each_with_index { |file, index| puts "#{index + 1}. #{file}" }
       input_index = Integer(gets.chomp)
       spec_file = arr[input_index - 1]
@@ -70,14 +70,14 @@ def find_spec_file
     exit
   end
 
-  spec_file.sub('./', '')
+  spec_file.sub("./", "")
 end
 
 def find_current_gem_file
   list_of_specs = execute_line("find . -name '*.gem'")
   arr = list_of_specs.split("\n")
 
-  spec_file = ''
+  spec_file = ""
 
   case arr.count
     when 0
@@ -86,7 +86,7 @@ def find_current_gem_file
     when 1
       spec_file = arr[0]
     else
-      puts 'Which spec should be used?'
+      puts "Which spec should be used?"
       arr.each_with_index { |file, index| puts "#{index + 1}. #{file}" }
       input_index = Integer(gets.chomp)
       spec_file = arr[input_index - 1]
@@ -97,7 +97,7 @@ def find_current_gem_file
     exit
   end
 
-  spec_file.sub('./', '')
+  spec_file.sub("./", "")
 end
 
 def find_version_in_podspec(podspec)
@@ -109,7 +109,7 @@ def find_version_in_podspec(podspec)
   match_result = re.match(readme)
 
   unless match_result
-    puts 'Not found any versions'
+    puts "Not found any versions"
     exit
   end
 
@@ -132,10 +132,10 @@ def bump_version(versions_array)
     when :patch
       bumped_result[2] += 1
     else
-      fail('unknown bump_number')
+      fail("unknown bump_number")
   end
 
-  bumped_version = bumped_result.join('.')
+  bumped_version = bumped_result.join(".")
   puts "Bump version: #{versions_array.join('.')} -> #{bumped_version}"
   bumped_version
 end
@@ -174,10 +174,10 @@ def run_bumping_script
   bumped_version = bump_version(versions_array)
 
   unless @options[:dry_run]
-    puts 'Are you sure? Press Y to continue:'
+    puts "Are you sure? Press Y to continue:"
     str = gets.chomp
-    if str != 'Y'
-      puts '-> exit'
+    if str != "Y"
+      puts "-> exit"
       exit
     end
   end
@@ -186,8 +186,8 @@ def run_bumping_script
   execute_line_if_not_dry_run("sed -i \"\" \"s/#{result}/#{bumped_version}/\" #{spec_file}")
   execute_line_if_not_dry_run("git commit --all -m \"Update #{$SPEC_TYPE} to version #{bumped_version}\"")
   execute_line_if_not_dry_run("git tag #{bumped_version}")
-  execute_line_if_not_dry_run('git push')
-  execute_line_if_not_dry_run('git push --tags')
+  execute_line_if_not_dry_run("git push")
+  execute_line_if_not_dry_run("git push --tags")
   execute_line_if_not_dry_run("gem build #{spec_file}")
 
   gem = find_current_gem_file
@@ -201,12 +201,12 @@ def revert_last_bump
 
   puts "DELETE tag #{result} and HARD reset HEAD~1?\nPress Y to continue:"
   str = gets.chomp
-  if str != 'Y'
-    puts '-> exit'
+  if str != "Y"
+    puts "-> exit"
     exit
   end
   execute_line_if_not_dry_run("git tag -d #{result}")
-  execute_line_if_not_dry_run('git reset --hard HEAD~1')
+  execute_line_if_not_dry_run("git reset --hard HEAD~1")
   execute_line_if_not_dry_run("git push --delete origin #{result}")
 end
 
diff --git a/github_changelog_generator.gemspec b/github_changelog_generator.gemspec
index 8452ee7..ff4c3cc 100644
--- a/github_changelog_generator.gemspec
+++ b/github_changelog_generator.gemspec
@@ -1,31 +1,31 @@
 # coding: utf-8
 
-lib = File.expand_path('../lib', __FILE__)
+lib = File.expand_path("../lib", __FILE__)
 $LOAD_PATH.unshift(lib) unless $LOAD_PATH.include?(lib)
-require 'github_changelog_generator/version'
+require "github_changelog_generator/version"
 
 Gem::Specification.new do |spec|
-  spec.name               = 'github_changelog_generator'
+  spec.name               = "github_changelog_generator"
   spec.version            = GitHubChangelogGenerator::VERSION
-  spec.default_executable = 'github_changelog_generator'
+  spec.default_executable = "github_changelog_generator"
 
-  spec.required_ruby_version     = '>= 1.9.3'
-  spec.authors = ['Petr Korolev']
-  spec.email = 'sky4winder+github_changelog_generator@gmail.com'
+  spec.required_ruby_version     = ">= 1.9.3"
+  spec.authors = ["Petr Korolev"]
+  spec.email = "sky4winder+github_changelog_generator@gmail.com"
   spec.date = `date +"%Y-%m-%d"`.strip!
-  spec.summary = 'Script, that automatically generate changelog from your tags, issues, labels and pull requests.'
-  spec.description = 'Changelog generation has never been so easy. Fully automate changelog generation - this gem generate change log file based on tags, issues and merged pull requests from Github issue tracker.'
-  spec.homepage = 'https://github.com/skywinder/Github-Changelog-Generator'
-  spec.license       = 'MIT'
+  spec.summary = "Script, that automatically generate changelog from your tags, issues, labels and pull requests."
+  spec.description = "Changelog generation has never been so easy. Fully automate changelog generation - this gem generate change log file based on tags, issues and merged pull requests from Github issue tracker."
+  spec.homepage = "https://github.com/skywinder/Github-Changelog-Generator"
+  spec.license       = "MIT"
 
   spec.files = `git ls-files -z`.split("\x0")
   spec.executables   = spec.files.grep(%r{^bin/}) { |f| File.basename(f) }
   spec.test_files    = spec.files.grep(%r{^(test|spec|features)/})
-  spec.require_paths = ['lib']
+  spec.require_paths = ["lib"]
 
-  spec.add_development_dependency 'bundler', '~> 1.7'
-  spec.add_development_dependency 'rake', '~> 10.0'
+  spec.add_development_dependency "bundler", "~> 1.7"
+  spec.add_development_dependency "rake", "~> 10.0"
 
-  spec.add_runtime_dependency('github_api', ['~> 0.12'])
-  spec.add_runtime_dependency('colorize', ['~> 0.7'])
+  spec.add_runtime_dependency("github_api", ["~> 0.12"])
+  spec.add_runtime_dependency("colorize", ["~> 0.7"])
 end
diff --git a/lib/github_changelog_generator.rb b/lib/github_changelog_generator.rb
index 7be9364..a92817e 100755
--- a/lib/github_changelog_generator.rb
+++ b/lib/github_changelog_generator.rb
@@ -1,22 +1,22 @@
 #!/usr/bin/env ruby
 
-require 'github_api'
-require 'json'
-require 'colorize'
-require 'benchmark'
+require "github_api"
+require "json"
+require "colorize"
+require "benchmark"
 
-require_relative 'github_changelog_generator/parser'
-require_relative 'github_changelog_generator/generator'
-require_relative 'github_changelog_generator/version'
-require_relative 'github_changelog_generator/reader'
+require_relative "github_changelog_generator/parser"
+require_relative "github_changelog_generator/generator"
+require_relative "github_changelog_generator/version"
+require_relative "github_changelog_generator/reader"
 
 module GitHubChangelogGenerator
   class ChangelogGenerator
     attr_accessor :options, :all_tags, :github
 
     PER_PAGE_NUMBER = 30
-    GH_RATE_LIMIT_EXCEEDED_MSG = 'Warning: GitHub API rate limit (5000 per hour) exceeded, change log may be ' \
-        'missing some issues. You can limit the number of issues fetched using the `--max-issues NUM` argument.'
+    GH_RATE_LIMIT_EXCEEDED_MSG = "Warning: GitHub API rate limit (5000 per hour) exceeded, change log may be " \
+        "missing some issues. You can limit the number of issues fetched using the `--max-issues NUM` argument."
 
     def initialize
       @options = Parser.parse_options
@@ -77,16 +77,16 @@ module GitHubChangelogGenerator
       threads.each(&:join)
 
       if @options[:verbose]
-        puts 'Fetching closed dates for issues: Done!'
+        puts "Fetching closed dates for issues: Done!"
       end
     end
 
     def find_closed_date_by_commit(issue)
-      unless issue['events'].nil?
+      unless issue["events"].nil?
         # if it's PR -> then find "merged event", in case of usual issue -> fond closed date
-        compare_string = issue[:merged_at].nil? ? 'closed' : 'merged'
+        compare_string = issue[:merged_at].nil? ? "closed" : "merged"
         # reverse! - to find latest closed event. (event goes in date order)
-        issue['events'].reverse!.each { |event|
+        issue["events"].reverse!.each { |event|
           if event[:event].eql? compare_string
             if event[:commit_id].nil?
               issue[:actual_date] = issue[:closed_at]
@@ -116,7 +116,7 @@ module GitHubChangelogGenerator
       end
       pull_requests = []
       begin
-        response = @github.pull_requests.list @options[:user], @options[:project], state: 'closed'
+        response = @github.pull_requests.list @options[:user], @options[:project], state: "closed"
         page_i = 0
         response.each_page do |page|
           page_i += PER_PAGE_NUMBER
@@ -139,7 +139,7 @@ module GitHubChangelogGenerator
       }
 
       if @options[:verbose]
-        puts 'Fetching merged dates: Done!'
+        puts "Fetching merged dates: Done!"
       end
     end
 
@@ -185,7 +185,7 @@ module GitHubChangelogGenerator
         tag1 = @options[:tag1]
         tag2 = @options[:tag2]
         tags_strings = []
-        all_tags.each { |x| tags_strings.push(x['name']) }
+        all_tags.each { |x| tags_strings.push(x["name"]) }
 
         if tags_strings.include?(tag1)
           if tags_strings.include?(tag2)
@@ -209,8 +209,8 @@ module GitHubChangelogGenerator
       log += "\n\n\\* *This Change Log was automatically generated by [github_changelog_generator](https://github.com/skywinder/Github-Changelog-Generator)*"
 
       output_filename = "#{@options[:output]}"
-      File.open(output_filename, 'w') { |file| file.write(log) }
-      puts 'Done!'
+      File.open(output_filename, "w") { |file| file.write(log) }
+      puts "Done!"
       puts "Generated log placed in #{`pwd`.strip!}/#{output_filename}"
     end
 
@@ -218,16 +218,16 @@ module GitHubChangelogGenerator
       fetch_tags_dates
 
       if @options[:verbose]
-        puts 'Sorting tags...'
+        puts "Sorting tags..."
       end
 
       @all_tags.sort_by! { |x| get_time_of_tag(x) }.reverse!
 
       if @options[:verbose]
-        puts 'Generating log...'
+        puts "Generating log..."
       end
 
-      log = ''
+      log = ""
 
       if @options[:unreleased] && @all_tags.count != 0
         unreleased_log = generate_log_between_tags(all_tags[0], nil)
@@ -307,11 +307,11 @@ module GitHubChangelogGenerator
     end
 
     def fetch_github_token
-      env_var = @options[:token] ? @options[:token] : (ENV.fetch 'CHANGELOG_GITHUB_TOKEN', nil)
+      env_var = @options[:token] ? @options[:token] : (ENV.fetch "CHANGELOG_GITHUB_TOKEN", nil)
 
       unless env_var
-        puts 'Warning: No token provided (-t option) and variable $CHANGELOG_GITHUB_TOKEN was not found.'.yellow
-        puts 'This script can make only 50 requests per hour to GitHub API without a token!'.yellow
+        puts "Warning: No token provided (-t option) and variable $CHANGELOG_GITHUB_TOKEN was not found.".yellow
+        puts "This script can make only 50 requests per hour to GitHub API without a token!".yellow
       end
 
       @github_token ||= env_var
@@ -322,8 +322,8 @@ module GitHubChangelogGenerator
       filtered_pull_requests = delete_by_time(@pull_requests, :actual_date, older_tag, newer_tag)
       filtered_issues = delete_by_time(@issues, :actual_date, older_tag, newer_tag)
 
-      newer_tag_name = newer_tag.nil? ? nil : newer_tag['name']
-      older_tag_name = older_tag.nil? ? nil : older_tag['name']
+      newer_tag_name = newer_tag.nil? ? nil : newer_tag["name"]
+      older_tag_name = older_tag.nil? ? nil : older_tag["name"]
 
       if @options[:filter_issues_by_milestone]
         # delete excess irrelevant issues (according milestones)
@@ -333,7 +333,7 @@ module GitHubChangelogGenerator
 
       if filtered_issues.empty? && filtered_pull_requests.empty? && newer_tag.nil?
         # do not generate empty unreleased section
-        return ''
+        return ""
       end
 
       create_log(filtered_pull_requests, filtered_issues, newer_tag, older_tag_name)
@@ -375,7 +375,7 @@ module GitHubChangelogGenerator
     end
 
     def delete_by_time(array, hash_key, older_tag = nil, newer_tag = nil)
-      fail 'At least one of the tags should be not nil!' if older_tag.nil? && newer_tag.nil?
+      fail "At least one of the tags should be not nil!" if older_tag.nil? && newer_tag.nil?
 
       newer_tag_time = get_time_of_tag(newer_tag)
       older_tag_time = get_time_of_tag(older_tag)
@@ -414,10 +414,10 @@ module GitHubChangelogGenerator
     # @return [String] Ready and parsed section
     def create_log(pull_requests, issues, newer_tag, older_tag_name = nil)
       newer_tag_time = newer_tag.nil? ? Time.new                    : get_time_of_tag(newer_tag)
-      newer_tag_name = newer_tag.nil? ? @options[:unreleased_label] : newer_tag['name']
-      newer_tag_link = newer_tag.nil? ? 'HEAD'                      : newer_tag_name
+      newer_tag_name = newer_tag.nil? ? @options[:unreleased_label] : newer_tag["name"]
+      newer_tag_link = newer_tag.nil? ? "HEAD"                      : newer_tag_name
 
-      github_site = options[:github_site] || 'https://github.com'
+      github_site = options[:github_site] || "https://github.com"
       project_url = "#{github_site}/#{@options[:user]}/#{@options[:project]}"
 
       log = generate_header(newer_tag_name, newer_tag_link, newer_tag_time, older_tag_name, project_url)
@@ -431,12 +431,12 @@ module GitHubChangelogGenerator
         issues.each { |dict|
           added = false
           dict.labels.each { |label|
-            if label.name == 'bug'
+            if label.name == "bug"
               bugs_a.push dict
               added = true
               next
             end
-            if label.name == 'enhancement'
+            if label.name == "enhancement"
               enhancement_a.push dict
               added = true
               next
@@ -464,7 +464,7 @@ module GitHubChangelogGenerator
     # @param [String] prefix Nae of sub-section
     # @return [String] Generate ready-to-go sub-section
     def generate_sub_section(issues, prefix)
-      log = ''
+      log = ""
 
       if options[:simple_list] != true && issues.any?
         log += "#{prefix}\n\n"
@@ -488,7 +488,7 @@ module GitHubChangelogGenerator
     # @param [String] project_url - url for current project.
     # @return [String] - Generate one ready-to-add section.
     def generate_header(newer_tag_name, newer_tag_link, newer_tag_time, older_tag_link, project_url)
-      log = ''
+      log = ""
 
       # Generate date string:
       time_string = newer_tag_time.strftime @options[:dateformat]
@@ -513,17 +513,17 @@ module GitHubChangelogGenerator
         return nil
       end
 
-      if tag_times_hash[tag_name['name']]
-        return @tag_times_hash[tag_name['name']]
+      if tag_times_hash[tag_name["name"]]
+        return @tag_times_hash[tag_name["name"]]
       end
 
       begin
-        github_git_data_commits_get = @github.git_data.commits.get @options[:user], @options[:project], tag_name['commit']['sha']
+        github_git_data_commits_get = @github.git_data.commits.get @options[:user], @options[:project], tag_name["commit"]["sha"]
       rescue
         puts GH_RATE_LIMIT_EXCEEDED_MSG.yellow
       end
-      time_string = github_git_data_commits_get['committer']['date']
-      @tag_times_hash[tag_name['name']] = Time.parse(time_string)
+      time_string = github_git_data_commits_get["committer"]["date"]
+      @tag_times_hash[tag_name["name"]] = Time.parse(time_string)
     end
 
     def get_filtered_issues
@@ -566,7 +566,7 @@ module GitHubChangelogGenerator
       issues = []
 
       begin
-        response = @github.issues.list user: @options[:user], repo: @options[:project], state: 'closed', filter: 'all', labels: nil
+        response = @github.issues.list user: @options[:user], repo: @options[:project], state: "closed", filter: "all", labels: nil
         page_i = 0
         count_pages = response.count_pages
         response.each_page do |page|
@@ -613,7 +613,7 @@ module GitHubChangelogGenerator
         issues_slice.each { |issue|
           threads << Thread.new {
             begin
-              obj = @github.issues.events.list user: @options[:user], repo: @options[:project], issue_number: issue['number']
+              obj = @github.issues.events.list user: @options[:user], repo: @options[:project], issue_number: issue["number"]
             rescue
               puts GH_RATE_LIMIT_EXCEEDED_MSG.yellow
             end
diff --git a/lib/github_changelog_generator/generator.rb b/lib/github_changelog_generator/generator.rb
index 2f47fd1..f076f4b 100644
--- a/lib/github_changelog_generator/generator.rb
+++ b/lib/github_changelog_generator/generator.rb
@@ -19,7 +19,7 @@ module GitHubChangelogGenerator
       unless issue.pull_request.nil?
         if @options[:author]
           if issue.user.nil?
-            title_with_number += ' ({Null user})'
+            title_with_number += " ({Null user})"
           else
             title_with_number += " ([#{issue.user.login}](#{issue.user.html_url}))"
           end
diff --git a/lib/github_changelog_generator/parser.rb b/lib/github_changelog_generator/parser.rb
index 46ecb67..0bb7b9d 100644
--- a/lib/github_changelog_generator/parser.rb
+++ b/lib/github_changelog_generator/parser.rb
@@ -1,7 +1,7 @@
 #!/usr/bin/env ruby
-require 'optparse'
-require 'pp'
-require_relative 'version'
+require "optparse"
+require "pp"
+require_relative "version"
 
 module GitHubChangelogGenerator
   class Parser
@@ -9,8 +9,8 @@ module GitHubChangelogGenerator
       options = {
         tag1: nil,
         tag2: nil,
-        dateformat: '%Y-%m-%d',
-        output: 'CHANGELOG.md',
+        dateformat: "%Y-%m-%d",
+        output: "CHANGELOG.md",
         issues: true,
         add_issues_wo_labels: true,
         add_pr_wo_labels: true,
@@ -18,7 +18,7 @@ module GitHubChangelogGenerator
         filter_issues_by_milestone: true,
         author: true,
         unreleased: true,
-        unreleased_label: 'Unreleased',
+        unreleased_label: "Unreleased",
         compare_link: true,
         include_labels: %w(bug enhancement),
         exclude_labels: %w(duplicate question invalid wontfix),
@@ -26,86 +26,86 @@ module GitHubChangelogGenerator
         simple_list: false,
         verbose: true,
 
-        merge_prefix: '**Merged pull requests:**',
-        issue_prefix: '**Closed issues:**',
-        bug_prefix: '**Fixed bugs:**',
-        enhancement_prefix: '**Implemented enhancements:**',
-        branch: 'origin'
+        merge_prefix: "**Merged pull requests:**",
+        issue_prefix: "**Closed issues:**",
+        bug_prefix: "**Fixed bugs:**",
+        enhancement_prefix: "**Implemented enhancements:**",
+        branch: "origin"
       }
 
       parser = OptionParser.new do |opts|
-        opts.banner = 'Usage: github_changelog_generator [options]'
-        opts.on('-u', '--user [USER]', 'Username of the owner of target GitHub repo') do |last|
+        opts.banner = "Usage: github_changelog_generator [options]"
+        opts.on("-u", "--user [USER]", "Username of the owner of target GitHub repo") do |last|
           options[:user] = last
         end
-        opts.on('-p', '--project [PROJECT]', 'Name of project on GitHub') do |last|
+        opts.on("-p", "--project [PROJECT]", "Name of project on GitHub") do |last|
           options[:project] = last
         end
-        opts.on('-t', '--token [TOKEN]', 'To make more than 50 requests per hour your GitHub token is required. You can generate it at: https://github.com/settings/tokens/new') do |last|
+        opts.on("-t", "--token [TOKEN]", "To make more than 50 requests per hour your GitHub token is required. You can generate it at: https://github.com/settings/tokens/new") do |last|
           options[:token] = last
         end
-        opts.on('-f', '--date-format [FORMAT]', 'Date format. Default is %Y-%m-%d') do |last|
+        opts.on("-f", "--date-format [FORMAT]", "Date format. Default is %Y-%m-%d") do |last|
           options[:dateformat] = last
         end
-        opts.on('-o', '--output [NAME]', 'Output file. Default is CHANGELOG.md') do |last|
+        opts.on("-o", "--output [NAME]", "Output file. Default is CHANGELOG.md") do |last|
           options[:output] = last
         end
-        opts.on('--[no-]issues', 'Include closed issues in changelog. Default is true') do |v|
+        opts.on("--[no-]issues", "Include closed issues in changelog. Default is true") do |v|
           options[:issues] = v
         end
-        opts.on('--[no-]issues-wo-labels', 'Include closed issues without labels in changelog. Default is true') do |v|
+        opts.on("--[no-]issues-wo-labels", "Include closed issues without labels in changelog. Default is true") do |v|
           options[:add_issues_wo_labels] = v
         end
-        opts.on('--[no-]pr-wo-labels', 'Include pull requests without labels in changelog. Default is true') do |v|
+        opts.on("--[no-]pr-wo-labels", "Include pull requests without labels in changelog. Default is true") do |v|
           options[:add_pr_wo_labels] = v
         end
-        opts.on('--[no-]pull-requests', 'Include pull-requests in changelog. Default is true') do |v|
+        opts.on("--[no-]pull-requests", "Include pull-requests in changelog. Default is true") do |v|
           options[:pulls] = v
         end
-        opts.on('--[no-]filter-by-milestone', 'Use milestone to detect when issue was resolved. Default is true') do |last|
+        opts.on("--[no-]filter-by-milestone", "Use milestone to detect when issue was resolved. Default is true") do |last|
           options[:filter_issues_by_milestone] = last
         end
-        opts.on('--[no-]author', 'Add author of pull-request in the end. Default is true') do |author|
+        opts.on("--[no-]author", "Add author of pull-request in the end. Default is true") do |author|
           options[:author] = author
         end
-        opts.on('--unreleased-only', 'Generate log from unreleased closed issues only.') do |v|
+        opts.on("--unreleased-only", "Generate log from unreleased closed issues only.") do |v|
           options[:unreleased_only] = v
         end
-        opts.on('--[no-]unreleased', 'Add to log unreleased closed issues. Default is true') do |v|
+        opts.on("--[no-]unreleased", "Add to log unreleased closed issues. Default is true") do |v|
           options[:unreleased] = v
         end
-        opts.on('--unreleased-label [label]', 'Add to log unreleased closed issues. Default is true') do |v|
+        opts.on("--unreleased-label [label]", "Add to log unreleased closed issues. Default is true") do |v|
           options[:unreleased_label] = v
         end
-        opts.on('--[no-]compare-link', 'Include compare link (Full Changelog) between older version and newer version. Default is true') do |v|
+        opts.on("--[no-]compare-link", "Include compare link (Full Changelog) between older version and newer version. Default is true") do |v|
           options[:compare_link] = v
         end
-        opts.on('--include-labels  x,y,z', Array, 'Only issues with the specified labels will be included in the changelog. Default is \'bug,enhancement\'') do |list|
+        opts.on("--include-labels  x,y,z", Array, 'Only issues with the specified labels will be included in the changelog. Default is \'bug,enhancement\'') do |list|
           options[:include_labels] = list
         end
-        opts.on('--exclude-labels  x,y,z', Array, 'Issues with the specified labels will be always excluded from changelog. Default is \'duplicate,question,invalid,wontfix\'') do |list|
+        opts.on("--exclude-labels  x,y,z", Array, 'Issues with the specified labels will be always excluded from changelog. Default is \'duplicate,question,invalid,wontfix\'') do |list|
           options[:exclude_labels] = list
         end
-        opts.on('--max-issues [NUMBER]', Integer, 'Max number of issues to fetch from GitHub. Default is unlimited') do |max|
+        opts.on("--max-issues [NUMBER]", Integer, "Max number of issues to fetch from GitHub. Default is unlimited") do |max|
           options[:max_issues] = max
         end
-        opts.on('--github-site [URL]', 'The Enterprise Github site on which your project is hosted.') do |last|
+        opts.on("--github-site [URL]", "The Enterprise Github site on which your project is hosted.") do |last|
           options[:github_site] = last
         end
-        opts.on('--github-api [URL]', 'The enterprise endpoint to use for your Github API.') do |last|
+        opts.on("--github-api [URL]", "The enterprise endpoint to use for your Github API.") do |last|
           options[:github_endpoint] = last
         end
-        opts.on('--simple-list', 'Create simple list from issues and pull requests. Default is false.') do |v|
+        opts.on("--simple-list", "Create simple list from issues and pull requests. Default is false.") do |v|
           options[:simple_list] = v
         end
-        opts.on('--[no-]verbose', 'Run verbosely. Default is true') do |v|
+        opts.on("--[no-]verbose", "Run verbosely. Default is true") do |v|
           options[:verbose] = v
         end
-        opts.on('-v', '--version', 'Print version number') do |_v|
+        opts.on("-v", "--version", "Print version number") do |_v|
           puts "Version: #{GitHubChangelogGenerator::VERSION}"
           exit
         end
-        opts.on('-h', '--help', 'Displays Help') do
+        opts.on("-h", "--help", "Displays Help") do
           puts opts
           exit
         end
@@ -114,7 +114,7 @@ module GitHubChangelogGenerator
       parser.parse!
 
       if ARGV[0] && !ARGV[1]
-        github_site = options[:github_site] ? options[:github_site] : 'github.com'
+        github_site = options[:github_site] ? options[:github_site] : "github.com"
         # this match should parse  strings such "https://github.com/skywinder/Github-Changelog-Generator" or "skywinder/Github-Changelog-Generator" to user and name
         match = /(?:.+#{Regexp.escape(github_site)}\/)?(.+)\/(.+)/.match(ARGV[0])
 
@@ -166,9 +166,9 @@ module GitHubChangelogGenerator
       end
 
       if options[:verbose]
-        puts 'Performing task with options:'
+        puts "Performing task with options:"
         pp options
-        puts ''
+        puts ""
       end
 
       options
diff --git a/lib/github_changelog_generator/reader.rb b/lib/github_changelog_generator/reader.rb
index fe1f61a..f46301f 100644
--- a/lib/github_changelog_generator/reader.rb
+++ b/lib/github_changelog_generator/reader.rb
@@ -25,7 +25,7 @@ module GitHubChangelogGenerator
   class Reader
     def initialize(options = {})
       defaults = {
-        heading_level: '##',
+        heading_level: "##",
         heading_structures: [
           /^## \[(?<version>.+?)\]\((?<url>.+?)\)( \((?<date>.+?)\))?$/,
           /^## (?<version>.+?)( \((?<date>.+?)\))?$/
@@ -49,7 +49,7 @@ module GitHubChangelogGenerator
     # @param [String] heading Heading from the ChangeLog File
     # @return [Hash] Returns a structured Hash with version, url and date
     def parse_heading(heading)
-      captures = { 'version' => nil, 'url' => nil, 'date' => nil }
+      captures = { "version" => nil, "url" => nil, "date" => nil }
 
       @heading_structures.each do |regexp|
         matches = Regexp.new(regexp).match(heading)
@@ -73,7 +73,7 @@ module GitHubChangelogGenerator
 
       headings.each_with_index do |heading, index|
         captures = parse_heading(heading)
-        captures['content'] = sections.at(index + 1)
+        captures["content"] = sections.at(index + 1)
         changelog.push captures
       end
 
diff --git a/lib/github_changelog_generator/version.rb b/lib/github_changelog_generator/version.rb
index 8b06a13..3d9ed6d 100644
--- a/lib/github_changelog_generator/version.rb
+++ b/lib/github_changelog_generator/version.rb
@@ -1,3 +1,3 @@
 module GitHubChangelogGenerator
-  VERSION = '1.3.11'
+  VERSION = "1.3.11"
 end
diff --git a/spec/spec_helper.rb b/spec/spec_helper.rb
index bcb64c3..dccfbf0 100644
--- a/spec/spec_helper.rb
+++ b/spec/spec_helper.rb
@@ -15,9 +15,9 @@
 # See the License for the specific language governing permissions and
 # limitations under the License.
 #
-require 'codeclimate-test-reporter'
-require 'simplecov'
-require 'coveralls'
+require "codeclimate-test-reporter"
+require "simplecov"
+require "coveralls"
 
 SimpleCov.formatter = SimpleCov::Formatter::MultiFormatter[
   Coveralls::SimpleCov::Formatter,
@@ -26,7 +26,7 @@ SimpleCov.formatter = SimpleCov::Formatter::MultiFormatter[
 ]
 SimpleCov.start
 
-require 'github_changelog_generator'
+require "github_changelog_generator"
 
 # This file was generated by the `rspec --init` command. Conventionally, all
 # specs live under a `spec` directory, which RSpec adds to the `$LOAD_PATH`.
@@ -95,7 +95,7 @@ RSpec.configure do |config|
     # Use the documentation formatter for detailed output,
     # unless a formatter has already been configured
     # (e.g. via a command-line flag).
-    config.default_formatter = 'doc'
+    config.default_formatter = "doc"
   end
 
   # Print the 10 slowest examples and example groups at the
diff --git a/spec/unit/reader_spec.rb b/spec/unit/reader_spec.rb
index c23a2df..f5a2ef9 100644
--- a/spec/unit/reader_spec.rb
+++ b/spec/unit/reader_spec.rb
@@ -21,71 +21,71 @@ describe GitHubChangelogGenerator::Reader do
     @reader = GitHubChangelogGenerator::Reader.new
   end
 
-  describe '#parse_heading' do
-    context 'when heading is empty' do
-      subject { @reader.parse_heading('## ') }
+  describe "#parse_heading" do
+    context "when heading is empty" do
+      subject { @reader.parse_heading("## ") }
       it { is_expected.to be_a(Hash) }
-      it { is_expected.to include('version', 'url', 'date') }
-      it { is_expected.to include('version' => nil, 'url' => nil, 'date' => nil) }
+      it { is_expected.to include("version", "url", "date") }
+      it { is_expected.to include("version" => nil, "url" => nil, "date" => nil) }
       # TODO: Doesn't work?
       # it { is_expected.to have_all_string_keys }
     end
-    context 'when given version, url and date' do
-      subject { @reader.parse_heading('## [1.3.10](https://github.com/skywinder/Github-Changelog-Generator/tree/1.3.10) (2015-03-18)') }
-      it { is_expected.to include('version' => '1.3.10') }
-      it { is_expected.to include('url' => 'https://github.com/skywinder/Github-Changelog-Generator/tree/1.3.10') }
-      it { is_expected.to include('date' => '2015-03-18') }
+    context "when given version, url and date" do
+      subject { @reader.parse_heading("## [1.3.10](https://github.com/skywinder/Github-Changelog-Generator/tree/1.3.10) (2015-03-18)") }
+      it { is_expected.to include("version" => "1.3.10") }
+      it { is_expected.to include("url" => "https://github.com/skywinder/Github-Changelog-Generator/tree/1.3.10") }
+      it { is_expected.to include("date" => "2015-03-18") }
     end
-    context 'when no url and date is provided' do
-      subject { @reader.parse_heading('## foobar') }
-      it { is_expected.to include('version' => 'foobar', 'url' => nil, 'date' => nil) }
+    context "when no url and date is provided" do
+      subject { @reader.parse_heading("## foobar") }
+      it { is_expected.to include("version" => "foobar", "url" => nil, "date" => nil) }
     end
   end
 
-  describe '#parse' do
-    context 'when file is empty' do
-      subject { @reader.parse('') }
+  describe "#parse" do
+    context "when file is empty" do
+      subject { @reader.parse("") }
       it { is_expected.to be_an(Array) }
       it { is_expected.to be_empty }
     end
-    context 'when file has only the header' do
-      subject { @reader.parse('# Change Log') }
+    context "when file has only the header" do
+      subject { @reader.parse("# Change Log") }
       it { is_expected.to be_an(Array) }
       it { is_expected.to be_empty }
     end
   end
 
-  describe 'example CHANGELOG files' do
-    subject { @reader.read(File.expand_path(File.join(File.dirname(__FILE__), '..', 'files', self.class.description))) }
-    context 'github-changelog-generator.md' do
+  describe "example CHANGELOG files" do
+    subject { @reader.read(File.expand_path(File.join(File.dirname(__FILE__), "..", "files", self.class.description))) }
+    context "github-changelog-generator.md" do
       it { is_expected.to be_an(Array) }
       it { is_expected.not_to be_empty }
       it { expect(subject.count).to eq(28) }
-      it { expect(subject.first).to include('version' => '1.3.10') }
-      it { expect(subject.first).to include('url' => 'https://github.com/skywinder/Github-Changelog-Generator/tree/1.3.10') }
-      it { expect(subject.first).to include('date' => '2015-03-18') }
-      it { expect(subject.first).to include('content') }
-      it 'content should not be empty' do
-        expect(subject.first['content']).not_to be_empty
+      it { expect(subject.first).to include("version" => "1.3.10") }
+      it { expect(subject.first).to include("url" => "https://github.com/skywinder/Github-Changelog-Generator/tree/1.3.10") }
+      it { expect(subject.first).to include("date" => "2015-03-18") }
+      it { expect(subject.first).to include("content") }
+      it "content should not be empty" do
+        expect(subject.first["content"]).not_to be_empty
       end
     end
-    context 'bundler.md' do
+    context "bundler.md" do
       it { is_expected.to be_an(Array) }
       it { is_expected.not_to be_empty }
       it { expect(subject.count).to eq(151) }
-      it { expect(subject.first).to include('version' => '1.9.1') }
-      it { expect(subject.first).to include('url' => nil) }
-      it { expect(subject.first).to include('date' => '2015-03-21') }
-      it { expect(subject.first).to include('content') }
-      it 'content should not be empty' do
-        expect(subject.first['content']).not_to be_empty
+      it { expect(subject.first).to include("version" => "1.9.1") }
+      it { expect(subject.first).to include("url" => nil) }
+      it { expect(subject.first).to include("date" => "2015-03-21") }
+      it { expect(subject.first).to include("content") }
+      it "content should not be empty" do
+        expect(subject.first["content"]).not_to be_empty
       end
     end
-    context 'angular.js.md' do
+    context "angular.js.md" do
       it { is_expected.to be_an(Array) }
       it { is_expected.not_to be_empty }
       it do
-        pending('Implement heading_level for parser.')
+        pending("Implement heading_level for parser.")
         expect(subject.count).to eq(134)
       end
       # it do