diff --git a/.travis.yml b/.travis.yml
index 1240a94..a17fba5 100644
--- a/.travis.yml
+++ b/.travis.yml
@@ -1,4 +1,4 @@
-dist: xenial  # Ubuntu 16.04 (required for python 3.7)
+dist: bionic  # Ubuntu 18.04 for new ruby version
 language: python
 python: 3.7
 branches:
@@ -6,13 +6,11 @@ branches:
   - gh-pages
   - /.*/
 before_install:
-  - sudo apt-key adv --keyserver keyserver.ubuntu.com --recv-keys E084DAB9
-  - echo "deb https://cran.rstudio.com/bin/linux/ubuntu trusty/" | sudo tee -a /etc/apt/sources.list
-  - sudo apt-get update -y
   - rvm default
   - gem install json kramdown jekyll
 install:
   - pip install pyyaml
 script:
+  - bundle config build.nokogiri --use-system-libraries
   - make lesson-check-all
   - make --always-make site