diff --git a/Gemfile b/Gemfile
index f7200f13..7f4f5e95 100644
--- a/Gemfile
+++ b/Gemfile
@@ -1,5 +1,5 @@
 # frozen_string_literal: true
 
-source 'http://rubygems.org'
+source 'https://rubygems.org'
 
 gemspec
diff --git a/README.md b/README.md
index 00e20797..016cd78f 100644
--- a/README.md
+++ b/README.md
@@ -72,7 +72,7 @@ Below is mostly comprehensive list of checks that HTMLProofer can perform.
 
 ### HTML
 
-* Whether your HTML markup is valid. This is done via [Nokogiri](http://www.nokogiri.org/tutorials/ensuring_well_formed_markup.html) to ensure well-formed markup.
+* Whether your HTML markup is valid. This is done via [Nokogumbo](https://github.com/rubys/nokogumbo) to validate well-formed HTML5 markup.
 
 ## Usage
 
@@ -222,7 +222,7 @@ htmlproofer --assume-extension ./_site
 
 ### Using through Docker
 
-If you have trouble with (or don't want to) install Ruby/Nokogiri, the command-line tool can be run through Docker. See [html-proofer-docker](https://github.com/18F/html-proofer-docker) for more information.
+If you have trouble with (or don't want to) install Ruby/Nokogumbo, the command-line tool can be run through Docker. See [html-proofer-docker](https://github.com/18F/html-proofer-docker) for more information.
 
 ### Using as Rack middleware
 
@@ -282,9 +282,10 @@ The `HTMLProofer` constructor takes an optional hash of additional options:
 | `check_external_hash` | Checks whether external hashes exist (even if the webpage exists). This slows the checker down. | `false` |
 | `check_favicon` | Enables the favicon checker. | `false` |
 | `check_opengraph` | Enables the Open Graph checker. | `false` |
-| `check_html` | Enables HTML validation errors from Nokogiri | `false` |
+| `check_html` | Enables HTML validation errors from Nokogumbo | `false` |
 | `check_img_http` | Fails an image if it's marked as `http` | `false` |
-|`checks_to_ignore`| An array of Strings indicating which checks you'd like to not perform. | `[]`
+| `check_sri` | Check that `<link>` and `<script>` external resources use SRI |false |
+| `checks_to_ignore`| An array of Strings indicating which checks you do not want to run | `[]`
 | `directory_index_file` | Sets the file to look for when a link refers to a directory. | `index.html` |
 | `disable_external` | If `true`, does not run the external link checker, which can take a lot of time. | `false` |
 | `empty_alt_ignore` | If `true`, ignores images with empty alt tags. | `false` |
@@ -314,15 +315,16 @@ See below for more information.
 
 ### Configuring HTML validation rules
 
-If `check_html` is `true`, Nokogiri performs additional validation on your HTML.
+If `check_html` is `true`, Nokogumbo performs additional validation on your HTML.
 
 You can pass in additional options to configure this validation.
 
 | Option | Description | Default |
 | :----- | :---------- | :------ |
-| `report_invalid_tags` | When `check_html` is enabled, HTML markup that is unknown to Nokogiri are reported as errors. | `false`
+| `report_invalid_tags` | When `check_html` is enabled, HTML markup that is unknown to Nokogumbo are reported as errors. | `false`
+| `report_missing_doctype` | When `check_html` is enabled, HTML markup with missing or out-of-order `DOCTYPE` are reported as errors. | `false`
 | `report_missing_names` | When `check_html` is enabled, HTML markup that are missing entity names are reported as errors. | `false`
-| `report_script_embeds` | When `check_html` is enabled, `script` tags containing markup [are reported as errors](http://git.io/vOovv). Enabling this option ignores those errors. | `false`
+| `report_script_embeds` | When `check_html` is enabled, `script` tags containing markup are reported as errors. | `false`
 
 For example:
 
diff --git a/bin/htmlproofer b/bin/htmlproofer
index d22bd203..dcbc5a0c 100755
--- a/bin/htmlproofer
+++ b/bin/htmlproofer
@@ -20,13 +20,13 @@ Mercenary.program(:htmlproofer) do |p|
   p.option 'as_links', '--as-links', 'Assumes that `PATH` is a comma-separated array of links to check.'
   p.option 'alt_ignore', '--alt-ignore image1,[image2,...]', Array, 'A comma-separated list of Strings or RegExps containing `img`s whose missing `alt` tags are safe to ignore'
   p.option 'assume_extension', '--assume-extension', 'Automatically add extension (e.g. `.html`) to file paths, to allow extensionless URLs (as supported by Jekyll 3 and GitHub Pages) (default: `false`).'
-  p.option 'checks_to_ignore', '--checks-to-ignore check1,[check2,...]', Array, ' An array of Strings indicating which checks you\'d like to not perform.'
+  p.option 'checks_to_ignore', '--checks-to-ignore check1,[check2,...]', Array, 'A comma-separated list of Strings indicating which checks you do not want to run (default: `[]`)'
   p.option 'check_external_hash', '--check-external-hash', 'Checks whether external hashes exist (even if the webpage exists). This slows the checker down (default: `false`).'
   p.option 'check_favicon', '--check-favicon', 'Enables the favicon checker (default: `false`).'
-  p.option 'check_html', '--check-html', 'Enables HTML validation errors from Nokogiri (default: `false`).'
+  p.option 'check_html', '--check-html', 'Enables HTML validation errors from Nokogumbo (default: `false`).'
   p.option 'check_img_http', '--check-img-http', 'Fails an image if it\'s marked as `http` (default: `false`).'
   p.option 'check_opengraph', '--check-opengraph', 'Enables the Open Graph checker (default: `false`).'
-  p.option 'check_sri', '--check-sri', 'Check that `<link>` and `<script>` external resources do use SRI (default: `false`).'
+  p.option 'check_sri', '--check-sri', 'Check that `<link>` and `<script>` external resources use SRI (default: `false`).'
   p.option 'directory_index_file', '--directory-index-file <filename>', String, 'Sets the file to look for when a link refers to a directory. (default: `index.html`)'
   p.option 'disable_external', '--disable-external', 'If `true`, does not run the external link checker, which can take a lot of time (default: `false`)'
   p.option 'empty_alt_ignore', '--empty-alt-ignore', 'If `true`, ignores images with empty alt tags'
@@ -37,9 +37,10 @@ Mercenary.program(:htmlproofer) do |p|
   p.option 'file_ignore', '--file-ignore file1,[file2,...]', Array, 'A comma-separated list of Strings or RegExps containing file paths that are safe to ignore'
   p.option 'http_status_ignore', '--http-status-ignore 123,[xxx, ...]', Array, 'A comma-separated list of numbers representing status codes to ignore.'
   p.option 'internal_domains', '--internal-domains domain1,[domain2,...]', Array, 'A comma-separated list of Strings containing domains that will be treated as internal urls.'
-  p.option 'report_invalid_tags', '--report-invalid-tags', 'Ignore `check_html` errors associated with unknown markup (default: `false`)'
-  p.option 'report_missing_names', '--report-missing-names', 'Ignore `check_html` errors associated with missing entities (default: `false`)'
-  p.option 'report_script_embeds', '--report-script-embeds', 'Ignore `check_html` errors associated with `script`s (default: `false`)'
+  p.option 'report_invalid_tags', '--report-invalid-tags', 'When `check_html` is enabled, HTML markup that is unknown to Nokogumbo are reported as errors (default: `false`)'
+  p.option 'report_missing_names', '--report-missing-names', 'When `check_html` is enabled, HTML markup that are missing entity names are reported as errors (default: `false`)'
+  p.option 'report_script_embeds', '--report-script-embeds', 'When `check_html` is enabled, `script` tags containing markup are reported as errors (default: `false`)'
+  p.option 'report_missing_doctype', '--report-missing-doctype', 'When `check_html` is enabled, HTML markup with missing or out-of-order `DOCTYPE` are reported as errors (default: `false`)'
   p.option 'log_level', '--log-level <level>', String, 'Sets the logging level, as determined by Yell. One of `:debug`, `:info`, `:warn`, `:error`, or `:fatal`. (default: `:info`)'
   p.option 'only_4xx', '--only-4xx', 'Only reports errors for links that fall within the 4xx status code range'
   p.option 'storage_dir', '--storage-dir PATH', String, 'Directory where to store the cache log (default: "tmp/.htmlproofer")'
@@ -80,6 +81,7 @@ Mercenary.program(:htmlproofer) do |p|
     options[:validation][:report_script_embeds] = opts['report_script_embeds'] unless opts['report_script_embeds'].nil?
     options[:validation][:report_missing_names] = opts['report_missing_names'] unless opts['report_missing_names'].nil?
     options[:validation][:report_invalid_tags] = opts['report_invalid_tags'] unless opts['report_invalid_tags'].nil?
+    options[:validation][:report_missing_doctype] = opts['report_missing_doctype'] unless opts['report_missing_doctype'].nil?
 
     options[:typhoeus] = HTMLProofer::Configuration.parse_json_option('typhoeus_config', opts['typhoeus_config']) unless opts['typhoeus_config'].nil?
 
diff --git a/html-proofer.gemspec b/html-proofer.gemspec
index edf6ac10..af096e48 100644
--- a/html-proofer.gemspec
+++ b/html-proofer.gemspec
@@ -20,7 +20,7 @@ Gem::Specification.new do |gem|
 
   gem.add_dependency 'addressable',     '~> 2.3'
   gem.add_dependency 'mercenary',       '~> 0.3'
-  gem.add_dependency 'nokogiri',        '~> 1.10'
+  gem.add_dependency 'nokogumbo',       '~> 2.0'
   gem.add_dependency 'parallel',        '~> 1.3'
   gem.add_dependency 'rainbow',         '~> 3.0'
   gem.add_dependency 'typhoeus',        '~> 1.3'
diff --git a/lib/html-proofer.rb b/lib/html-proofer.rb
index 92ef0df0..1900fa15 100644
--- a/lib/html-proofer.rb
+++ b/lib/html-proofer.rb
@@ -17,7 +17,7 @@ def require_all(path)
 begin
   require 'awesome_print'
   require 'pry-byebug'
-rescue LoadError; end # rubocop:disable Lint/HandleExceptions
+rescue LoadError; end # rubocop:disable Lint/SuppressedException
 module HTMLProofer
   def self.check_file(file, options = {})
     raise ArgumentError unless file.is_a?(String)
diff --git a/lib/html-proofer/check/html.rb b/lib/html-proofer/check/html.rb
index 9580c44c..ea6b64c3 100644
--- a/lib/html-proofer/check/html.rb
+++ b/lib/html-proofer/check/html.rb
@@ -1,28 +1,31 @@
 # frozen_string_literal: true
 
 class HtmlCheck < ::HTMLProofer::Check
+  # tags embedded in scripts are used in templating languages: http://git.io/vOovv
   SCRIPT_EMBEDS_MSG = /Element script embeds close tag/.freeze
   INVALID_TAG_MSG = /Tag ([\w\-:]+) invalid/.freeze
   INVALID_PREFIX = /Namespace prefix/.freeze
   PARSE_ENTITY_REF = /htmlParseEntityRef: no name/.freeze
+  DOCTYPE_MSG = /The doctype must be the first token in the document/.freeze
 
   def run
     @html.errors.each do |error|
-      message = error.message
-      line    = error.line
-
-      if message =~ INVALID_TAG_MSG || message =~ INVALID_PREFIX
-        next unless options[:validation][:report_invalid_tags]
-      end
-
-      if message =~ PARSE_ENTITY_REF
-        next unless options[:validation][:report_missing_names]
-      end
-
-      # tags embedded in scripts are used in templating languages: http://git.io/vOovv
-      next if !options[:validation][:report_script_embeds] && message =~ SCRIPT_EMBEDS_MSG
+      add_issue(error.message, line: error.line) if report?(error.message)
+    end
+  end
 
-      add_issue(message, line: line)
+  def report?(message)
+    case message
+    when SCRIPT_EMBEDS_MSG
+      options[:validation][:report_script_embeds]
+    when INVALID_TAG_MSG, INVALID_PREFIX
+      options[:validation][:report_invalid_tags]
+    when PARSE_ENTITY_REF
+      options[:validation][:report_missing_names]
+    when DOCTYPE_MSG
+      options[:validation][:report_missing_doctype]
+    else
+      true
     end
   end
 end
diff --git a/lib/html-proofer/check/links.rb b/lib/html-proofer/check/links.rb
index e35c1879..02535a29 100644
--- a/lib/html-proofer/check/links.rb
+++ b/lib/html-proofer/check/links.rb
@@ -34,7 +34,7 @@ def run
       if missing_href?
         next if @link.allow_missing_href?
         # HTML5 allows dropping the href: http://git.io/vBX0z
-        next if @html.internal_subset.name == 'html' && @html.internal_subset.external_id.nil?
+        next if @html.internal_subset.nil? || (@html.internal_subset.name == 'html' && @html.internal_subset.external_id.nil?)
 
         add_issue('anchor has no href attribute', line: line, content: content)
         next
diff --git a/lib/html-proofer/configuration.rb b/lib/html-proofer/configuration.rb
index 187d4bdb..d8ccc09b 100644
--- a/lib/html-proofer/configuration.rb
+++ b/lib/html-proofer/configuration.rb
@@ -51,7 +51,8 @@ module Configuration
     VALIDATION_DEFAULTS = {
       report_script_embeds: false,
       report_missing_names: false,
-      report_invalid_tags: false
+      report_invalid_tags: false,
+      report_missing_doctype: false
     }.freeze
 
     CACHE_DEFAULTS = {}.freeze
diff --git a/lib/html-proofer/middleware.rb b/lib/html-proofer/middleware.rb
index b3e2a704..5339d547 100644
--- a/lib/html-proofer/middleware.rb
+++ b/lib/html-proofer/middleware.rb
@@ -69,7 +69,7 @@ def call(env)
           'response',
           Middleware.options
         ).check_parsed(
-          Nokogiri::HTML(clean_content(html)), 'response'
+          Nokogiri::HTML5(html, max_errors: -1), 'response'
         )
 
         raise InvalidHtmlError, parsed[:failures] unless parsed[:failures].empty?
diff --git a/lib/html-proofer/url_validator.rb b/lib/html-proofer/url_validator.rb
index e6496400..69d32c2a 100644
--- a/lib/html-proofer/url_validator.rb
+++ b/lib/html-proofer/url_validator.rb
@@ -146,7 +146,7 @@ def response_handler(response, filenames)
       href = response.request.base_url.to_s
       method = response.request.options[:method]
       response_code = response.code
-      response.body.gsub!("\x00", '')
+      response.body.delete!("\x00")
 
       debug_msg = if filenames.nil?
                     "Received a #{response_code} for #{href}"
diff --git a/lib/html-proofer/utils.rb b/lib/html-proofer/utils.rb
index d792ad08..523df91a 100644
--- a/lib/html-proofer/utils.rb
+++ b/lib/html-proofer/utils.rb
@@ -1,6 +1,6 @@
 # frozen_string_literal: true
 
-require 'nokogiri'
+require 'nokogumbo'
 
 module HTMLProofer
   module Utils
@@ -15,7 +15,7 @@ def create_nokogiri(path)
                   path
                 end
 
-      Nokogiri::HTML(clean_content(content))
+      Nokogiri::HTML5(content)
     end
 
     def swap(href, replacement)
@@ -24,14 +24,5 @@ def swap(href, replacement)
       end
       href
     end
-
-    # address a problem with Nokogiri's parsing URL entities
-    # problem from http://git.io/vBYU1
-    # solution from http://git.io/vBYUi
-    def clean_content(string)
-      string.gsub(%r{(?:https?:)?//([^>]+)}i) do |url|
-        url.gsub(/&(?!amp;)/, '&amp;')
-      end
-    end
   end
 end
diff --git a/spec/html-proofer/command_spec.rb b/spec/html-proofer/command_spec.rb
index 9e37e196..0eafddde 100644
--- a/spec/html-proofer/command_spec.rb
+++ b/spec/html-proofer/command_spec.rb
@@ -89,9 +89,9 @@
   end
 
   it 'works with check-html' do
-    broken = "#{FIXTURES_DIR}/html/invalid_tag.html"
+    broken = "#{FIXTURES_DIR}/html/unmatched_end_tag.html"
     output = make_bin('--check-html --report-invalid-tags', broken)
-    expect(output).to match('1 failure')
+    expect(output).to match('HTML-Proofer finished successfully')
   end
 
   it 'works with empty-alt-ignore' do
@@ -106,25 +106,38 @@
     expect(output).to match('successfully')
   end
 
-  it 'has every option' do
-    config_keys = HTMLProofer::Configuration::PROOFER_DEFAULTS.keys
-    bin_file = File.read('bin/htmlproofer')
-    help_output = make_bin('--help')
-    readme = File.read('README.md')
-    config_keys.map(&:to_s).each do |key|
-      # match options
-      expect(bin_file).to match(key)
-      readme.each_line do |line|
-        next unless line =~ /\| `#{key}`/
-
-        description = line.split('|')[2].strip
-        description.gsub!('A hash', 'A comma-separated list')
-        description.gsub!('An array', 'A comma-separated list')
-        description.gsub!(/\[(.+?)\]\(.+?\)/, '\1')
-        description.sub!(/\.$/, '')
-        # match README description for option
-        expect(help_output).to include(description)
-      end
+  it 'has every option for proofer defaults' do
+    match_command_help(HTMLProofer::Configuration::PROOFER_DEFAULTS)
+  end
+
+  it 'has every option for validation defaults' do
+    match_command_help(HTMLProofer::Configuration::VALIDATION_DEFAULTS)
+  end
+end
+
+def match_command_help(config)
+  config_keys = config.keys
+  bin_file = File.read('bin/htmlproofer')
+  help_output = make_bin('--help')
+  readme = File.read('README.md')
+
+  config_keys.map(&:to_s).each do |key|
+    # match options
+    expect(bin_file).to match(key)
+    matched = false
+    readme.each_line do |line|
+      next unless line =~ /\| `#{key}`/
+
+      matched = true
+      description = line.split('|')[2].strip
+      description.gsub!('A hash', 'A comma-separated list')
+      description.gsub!('An array', 'A comma-separated list')
+      description.gsub!(/\[(.+?)\]\(.+?\)/, '\1')
+      description.sub!(/\.$/, '')
+      # match README description for option
+      expect(help_output).to include(description)
     end
+
+    expect(matched).to be(true), "Could not find `#{key}` explained in README!" unless matched
   end
 end
diff --git a/spec/html-proofer/element_spec.rb b/spec/html-proofer/element_spec.rb
index 52d0c62a..92fa5007 100644
--- a/spec/html-proofer/element_spec.rb
+++ b/spec/html-proofer/element_spec.rb
@@ -4,24 +4,24 @@
 
 describe HTMLProofer::Element do
   before(:each) do
-    @check = HTMLProofer::Check.new('', '', Nokogiri::HTML(''), HTMLProofer::Configuration::PROOFER_DEFAULTS)
+    @check = HTMLProofer::Check.new('', '', Nokogiri::HTML5(''), HTMLProofer::Configuration::PROOFER_DEFAULTS)
   end
 
   describe '#initialize' do
     it 'accepts the xmlns attribute' do
-      nokogiri = Nokogiri::HTML('<a xmlns:cc="http://creativecommons.org/ns#">Creative Commons</a>')
+      nokogiri = Nokogiri::HTML5('<a xmlns:cc="http://creativecommons.org/ns#">Creative Commons</a>')
       checkable = HTMLProofer::Element.new(nokogiri.css('a').first, @check)
       expect(checkable.instance_variable_get(:@xmlns_cc)).to eq 'http://creativecommons.org/ns#'
     end
 
     it 'assignes the text node' do
-      nokogiri = Nokogiri::HTML('<p>One')
+      nokogiri = Nokogiri::HTML5('<p>One')
       checkable = HTMLProofer::Element.new(nokogiri.css('p').first, @check)
       expect(checkable.instance_variable_get(:@text)).to eq 'One'
     end
 
     it 'accepts the content attribute' do
-      nokogiri = Nokogiri::HTML('<meta name="twitter:card" content="summary">')
+      nokogiri = Nokogiri::HTML5('<meta name="twitter:card" content="summary">')
       checkable = HTMLProofer::Element.new(nokogiri.css('meta').first, @check)
       expect(checkable.instance_variable_get(:@content)).to eq 'summary'
     end
@@ -29,13 +29,13 @@
 
   describe '#ignores_pattern_check' do
     it 'works for regex patterns' do
-      nokogiri = Nokogiri::HTML('<script src=/assets/main.js></script>')
+      nokogiri = Nokogiri::HTML5('<script src=/assets/main.js></script>')
       checkable = HTMLProofer::Element.new(nokogiri.css('script').first, @check)
       expect(checkable.ignores_pattern_check([%r{\/assets\/.*(js|css|png|svg)}])).to eq true
     end
 
     it 'works for string patterns' do
-      nokogiri = Nokogiri::HTML('<script src=/assets/main.js></script>')
+      nokogiri = Nokogiri::HTML5('<script src=/assets/main.js></script>')
       checkable = HTMLProofer::Element.new(nokogiri.css('script').first, @check)
       expect(checkable.ignores_pattern_check(['/assets/main.js'])).to eq true
     end
@@ -43,7 +43,7 @@
 
   describe '#url' do
     it 'works for src attributes' do
-      nokogiri = Nokogiri::HTML('<img src=image.png />')
+      nokogiri = Nokogiri::HTML5('<img src=image.png />')
       checkable = HTMLProofer::Element.new(nokogiri.css('img').first, @check)
       expect(checkable.url).to eq 'image.png'
     end
@@ -51,7 +51,7 @@
 
   describe '#ignore' do
     it 'works for twitter cards' do
-      nokogiri = Nokogiri::HTML('<meta name="twitter:url" data-proofer-ignore content="http://example.com/soon-to-be-published-url">')
+      nokogiri = Nokogiri::HTML5('<meta name="twitter:url" data-proofer-ignore content="http://example.com/soon-to-be-published-url">')
       checkable = HTMLProofer::Element.new(nokogiri.css('meta').first, @check)
       expect(checkable.ignore?).to eq true
     end
diff --git a/spec/html-proofer/fixtures/html/html5_tags.html b/spec/html-proofer/fixtures/html/html5_tags.html
index 0ad4ae71..9b9af6ff 100644
--- a/spec/html-proofer/fixtures/html/html5_tags.html
+++ b/spec/html-proofer/fixtures/html/html5_tags.html
@@ -1,9 +1,9 @@
+<!DOCTYPE html>
 <html>
-<body>
-<nav>
-</nav>
-<article>
-<p>Some text</p>
-</article>
-</body>
+  <body>
+    <nav></nav>
+    <article>
+      <p>Some text</p>
+    </article>
+  </body>
 </html>
diff --git a/spec/html-proofer/fixtures/html/weird_onclick.html b/spec/html-proofer/fixtures/html/weird_onclick.html
index 3ca33457..ee58f094 100644
--- a/spec/html-proofer/fixtures/html/weird_onclick.html
+++ b/spec/html-proofer/fixtures/html/weird_onclick.html
@@ -1 +1 @@
-<a href="http://www.google.com" onClick="window.open('https://calendar.google.com/calendar/embed?src=o3uckm13gkcc5tu4u3846ik0pc%40group.calendar.google.com&ctz=America/Los_Angeles','Team Calendar','')">
+<a href="http://www.google.com" onClick="window.open('https://calendar.google.com/calendar/embed?src=o3uckm13gkcc5tu4u3846ik0pc%40group.calendar.google.com&ctz=America/Los_Angeles','Team Calendar','')"></a>
diff --git a/spec/html-proofer/html_spec.rb b/spec/html-proofer/html_spec.rb
index d2c7dd07..76cbe909 100644
--- a/spec/html-proofer/html_spec.rb
+++ b/spec/html-proofer/html_spec.rb
@@ -21,40 +21,40 @@
     expect(proofer.failed_tests).to eq []
   end
 
-  it 'fails for an invalid tag' do
+  it 'works for custom tags' do
     html = "#{FIXTURES_DIR}/html/invalid_tag.html"
     proofer = run_proofer(html, :file, check_html: true, validation: { report_invalid_tags: true })
-    expect(proofer.failed_tests.first).to match(/Tag myfancytag invalid \(line 2\)/)
+    expect(proofer.failed_tests).to eq []
   end
 
-  it 'fails for an unmatched end tag' do
+  it 'allows an unmatched end tag' do
     html = "#{FIXTURES_DIR}/html/unmatched_end_tag.html"
     proofer = run_proofer(html, :file, check_html: true)
-    expect(proofer.failed_tests.first).to match(/Unexpected end tag : div \(line 3\)/)
+    expect(proofer.failed_tests).to eq []
   end
 
-  it 'fails for an unescaped ampersand in attribute' do
+  it 'allows an unescaped ampersand in attribute' do
     html = "#{FIXTURES_DIR}/html/unescaped_ampersand_in_attribute.html"
     proofer = run_proofer(html, :file, check_html: true)
-    expect(proofer.failed_tests.first).to match(/htmlParseEntityRef: expecting ';' \(line 2\)/)
+    expect(proofer.failed_tests).to eq []
   end
 
-  it 'fails for mismatch between opening and ending tag' do
+  it 'allows mismatch between opening and ending tag' do
     html = "#{FIXTURES_DIR}/html/opening_and_ending_tag_mismatch.html"
     proofer = run_proofer(html, :file, check_html: true)
-    expect(proofer.failed_tests.first).to match(/Opening and ending tag mismatch: p and strong/)
+    expect(proofer.failed_tests).to eq []
   end
 
-  it 'fails for div inside head' do
+  it 'allows div inside head' do
     html = "#{FIXTURES_DIR}/html/div_inside_head.html"
     proofer = run_proofer(html, :file, check_html: true)
-    expect(proofer.failed_tests.first).to match(/Unexpected end tag : head \(line 5\)/)
+    expect(proofer.failed_tests).to eq []
   end
 
-  it 'fails for missing closing quotation mark in href' do
+  it 'allows missing closing quotation mark in href' do
     html = "#{FIXTURES_DIR}/html/missing_closing_quotes.html"
     proofer = run_proofer(html, :file, check_html: true)
-    expect(proofer.failed_tests.to_s).to match(/Couldn't find end of Start Tag a \(line 6\)/)
+    expect(proofer.failed_tests).to eq []
   end
 
   it "doesn't fail for single ampersand" do
@@ -63,10 +63,10 @@
     expect(proofer.failed_tests).to eq []
   end
 
-  it 'fails for single ampersand when asked' do
+  it 'allows single ampersand' do
     html = "#{FIXTURES_DIR}/html/single_amp.html"
     proofer = run_proofer(html, :file, check_html: true, validation: { report_missing_names: true })
-    expect(proofer.failed_tests.first).to match('htmlParseEntityRef: no name')
+    expect(proofer.failed_tests).to eq []
   end
 
   it 'ignores embeded scripts when asked' do
@@ -80,7 +80,7 @@
     opts = { check_html: true, validation: { report_script_embeds: true } }
     ignorable_script = "#{FIXTURES_DIR}/html/ignore_script_embeds.html"
     proofer = run_proofer(ignorable_script, :file, opts)
-    expect(proofer.failed_tests.length).to eq 2
+    expect(proofer.failed_tests).to eq []
   end
 
   it 'does not fail for weird iframe sources' do
diff --git a/spec/html-proofer/links_spec.rb b/spec/html-proofer/links_spec.rb
index aa786fe0..e67dbf81 100644
--- a/spec/html-proofer/links_spec.rb
+++ b/spec/html-proofer/links_spec.rb
@@ -97,10 +97,10 @@
     expect(proofer.failed_tests).to eq []
   end
 
-  it 'fails for link with no href' do
+  it 'allows link with no href' do
     missing_link_href_filepath = "#{FIXTURES_DIR}/links/missing_link_href.html"
     proofer = run_proofer(missing_link_href_filepath, :file)
-    expect(proofer.failed_tests.first).to match(/anchor has no href attribute/)
+    expect(proofer.failed_tests).to eq []
   end
 
   it 'should follow redirects' do
@@ -247,16 +247,16 @@
     expect(proofer.failed_tests).to eq []
   end
 
-  it 'fails for empty href within link elements' do
+  it 'allows empty href on link elements' do
     head_link = "#{FIXTURES_DIR}/links/head_link_href_empty.html"
     proofer = run_proofer(head_link, :file)
-    expect(proofer.failed_tests.first).to match(/anchor has no href attribute/)
+    expect(proofer.failed_tests).to eq []
   end
 
-  it 'fails for absent href within link elements' do
+  it 'allows missing href on link elements' do
     head_link = "#{FIXTURES_DIR}/links/head_link_href_absent.html"
     proofer = run_proofer(head_link, :file)
-    expect(proofer.failed_tests.first).to match(/anchor has no href attribute/)
+    expect(proofer.failed_tests).to eq []
   end
 
   it 'fails for internal linking to a directory without trailing slash' do
@@ -366,10 +366,10 @@
     expect(proofer.failed_tests).to eq []
   end
 
-  it 'fails for placeholder with empty id' do
+  it 'allows placeholder with empty id' do
     empty_id = "#{FIXTURES_DIR}/links/placeholder_with_empty_id.html"
     proofer = run_proofer(empty_id, :file)
-    expect(proofer.failed_tests.first).to match(/anchor has no href attribute/)
+    expect(proofer.failed_tests).to eq []
   end
 
   it 'ignores non-http(s) protocols' do
@@ -525,7 +525,7 @@
 
     missing_href = "#{FIXTURES_DIR}/links/blank_href_htmlunknown.html"
     proofer = run_proofer(missing_href, :file)
-    expect(proofer.failed_tests.length).to eq 1
+    expect(proofer.failed_tests).to eq []
   end
 
   it 'can skip expecting href for anchors in non-HTML5' do
diff --git a/spec/html-proofer/scripts_spec.rb b/spec/html-proofer/scripts_spec.rb
index 8675894e..563c02da 100644
--- a/spec/html-proofer/scripts_spec.rb
+++ b/spec/html-proofer/scripts_spec.rb
@@ -18,7 +18,8 @@
   it 'fails for missing internal src' do
     file = "#{FIXTURES_DIR}/scripts/script_missing_internal.html"
     proofer = run_proofer(file, :file)
-    expect(proofer.failed_tests.first).to match(/doesnotexist.js does not exist \(line 5\)/)
+    expect(proofer.failed_tests.length).to eq 1
+    expect(proofer.failed_tests.first).to include('spec/html-proofer/fixtures/scripts/script_missing_internal.html: internal script doesnotexist.js does not exist (line 5)')
   end
 
   it 'works for present content' do
diff --git a/spec/spec_helper.rb b/spec/spec_helper.rb
index f9fcf900..dd63e917 100644
--- a/spec/spec_helper.rb
+++ b/spec/spec_helper.rb
@@ -34,7 +34,7 @@ def capture_stderr(*)
   $stdout = StringIO.new unless ENV['VERBOSE']
   begin
     yield
-  rescue RuntimeError # rubocop:disable Lint/HandleExceptions
+  rescue RuntimeError # rubocop:disable Lint/SuppressedException
   ensure
     $stderr = original_stderr
     $stdout = original_stdout unless ENV['VERBOSE']