diff --git a/.travis.yml b/.travis.yml
index e69de1c9..fe14e1ce 100644
--- a/.travis.yml
+++ b/.travis.yml
@@ -2,9 +2,22 @@ language: ruby
 rvm:
   - 2.4.1
 
+addons:
+  apt:
+    packages:
+      - openjdk-8-jre  # install Java8 as required by vnu.jar
+      - python3
+      - python3-pip
+      - python3-wheel
+
+install:
+  - pip3 install html5validator --user
+
 # Assume bundler is being used, therefore
 # the `install` step will run `bundle install` by default.
-script: ./build.sh
+script:
+  - ./build.sh
+  - html5validator --root _site/ --also-check-css --blacklist classic
 
 sudo: false # route your build to the container-based infrastructure for a faster build
 
diff --git a/build.sh b/build.sh
index ebe27b86..cfbd379a 100755
--- a/build.sh
+++ b/build.sh
@@ -1,4 +1,5 @@
 #!/usr/bin/env bash
 set -e # halt script on error
 
-bundle exec jekyll build
+bundle install
+bundle exec jekyll build --profile