diff --git a/.travis.yml b/.travis.yml
index b2ab4d3..45db7f6 100644
--- a/.travis.yml
+++ b/.travis.yml
@@ -3,15 +3,24 @@ cache: bundler
 rvm:
   - 2.2.5
 
-#before_script:
-# - chmod +x ./script/cibuild # or do this locally and commit
+before_script:
+ - chmod +x ./script/cibuild # or do this locally and commit
 
 # Assume bundler is being used, therefore
 # the `install` step will run `bundle install` by default.
-script: bundle exec jekyll build
+script: ./script/cibuild
 # http://stackoverflow.com/questions/28611513/travis-build-failing-on-jekyll-project-cannot-find-jekyll
 # for html5proof ./script/cibuild && jekyll build && htmlproofer ./_site
-sudo: required
+sudo: false
+
+# branch whitelist, only for GitHub Pages
+branches:
+  only:
+  - master
+
+env:
+  global:
+  - NOKOGIRI_USE_SYSTEM_LIBRARIES=true # speeds up installation of html-proofer
 
 notifications:
   webhooks:
@@ -20,3 +29,4 @@ notifications:
     on_success: always  # options: [always|never|change] default: always
     on_failure: always  # options: [always|never|change] default: always
     on_start: false     # default: false
+
diff --git a/Gemfile b/Gemfile
index ec513b3..9739ef6 100644
--- a/Gemfile
+++ b/Gemfile
@@ -17,6 +17,9 @@ gem "minima", "~> 2.0"
 # sitemap
 gem 'jekyll-sitemap'
 
+# html-proofer for testing
+gem 'html-proofer'
+
 # If you want to use GitHub Pages, remove the "gem "jekyll"" above and
 # uncomment the line below. To upgrade, run `bundle update github-pages`.
 # gem "github-pages", group: :jekyll_plugins
diff --git a/Gemfile.lock b/Gemfile.lock
index 192bf88..245da5b 100644
--- a/Gemfile.lock
+++ b/Gemfile.lock
@@ -1,11 +1,30 @@
 GEM
   remote: https://rubygems.org/
   specs:
+    activesupport (5.0.1)
+      concurrent-ruby (~> 1.0, >= 1.0.2)
+      i18n (~> 0.7)
+      minitest (~> 5.1)
+      tzinfo (~> 1.1)
     addressable (2.5.0)
       public_suffix (~> 2.0, >= 2.0.2)
     colorator (1.1.0)
+    colored (1.2)
+    concurrent-ruby (1.0.4)
+    ethon (0.10.1)
+      ffi (>= 1.3.0)
     ffi (1.9.14)
     forwardable-extended (2.6.0)
+    html-proofer (3.4.0)
+      activesupport (>= 4.2, < 6.0)
+      addressable (~> 2.3)
+      colored (~> 1.2)
+      mercenary (~> 0.3.2)
+      nokogiri (~> 1.5)
+      parallel (~> 1.3)
+      typhoeus (~> 0.7)
+      yell (~> 2.0)
+    i18n (0.8.0)
     jekyll (3.3.0)
       addressable (~> 2.4)
       colorator (~> 1.0)
@@ -31,8 +50,13 @@ GEM
       rb-fsevent (~> 0.9, >= 0.9.4)
       rb-inotify (~> 0.9, >= 0.9.7)
     mercenary (0.3.6)
+    mini_portile2 (2.1.0)
     minima (2.1.0)
       jekyll (~> 3.3)
+    minitest (5.10.1)
+    nokogiri (1.7.0.1)
+      mini_portile2 (~> 2.1.0)
+    parallel (1.10.0)
     pathutil (0.14.0)
       forwardable-extended (~> 2.6)
     public_suffix (2.0.4)
@@ -42,11 +66,18 @@ GEM
     rouge (1.11.1)
     safe_yaml (1.0.4)
     sass (3.4.22)
+    thread_safe (0.3.5)
+    typhoeus (0.8.0)
+      ethon (>= 0.8.0)
+    tzinfo (1.2.2)
+      thread_safe (~> 0.1)
+    yell (2.0.7)
 
 PLATFORMS
   ruby
 
 DEPENDENCIES
+  html-proofer
   jekyll (= 3.3.0)
   jekyll-feed (~> 0.6)
   jekyll-sitemap
diff --git a/_config.yml b/_config.yml
index 24d6346..99e70f1 100644
--- a/_config.yml
+++ b/_config.yml
@@ -28,6 +28,7 @@ theme: minima
 gems:
   - jekyll-feed
   - jekyll-sitemap
+  - html-proofer
 
 sass:
   sass_dir: css/partials
@@ -37,6 +38,8 @@ exclude:
   - Gemfile
   - Gemfile.lock
   - vendor
+  - misc
+  - script
 
 # Be sure to exclude vendor from your  _config.yml
 # Travis bundles all gems in the vendor directory on its build servers, which Jekyll will mistakenly read and explode on.
diff --git a/script/cibuild b/script/cibuild
new file mode 100644
index 0000000..2f716f8
--- /dev/null
+++ b/script/cibuild
@@ -0,0 +1,5 @@
+#!/usr/bin/env bash
+set -e # halt script on error
+
+bundle exec jekyll build
+bundle exec htmlproofer ./_site --allow-hash-href --check-favicon --check-opengraph --check-html
\ No newline at end of file