diff --git a/.travis.yml b/.travis.yml
index 43261e6..a8e7507 100644
--- a/.travis.yml
+++ b/.travis.yml
@@ -1,6 +1,8 @@
 language: ruby
 rvm:
   - 2.6
+before_install:
+  - gem install bundler
 script:
   - jekyll build --drafts
 deploy:
diff --git a/jekyll-theme-bootstrap4.gemspec b/jekyll-theme-bootstrap4.gemspec
index f783a2a..103891f 100644
--- a/jekyll-theme-bootstrap4.gemspec
+++ b/jekyll-theme-bootstrap4.gemspec
@@ -11,8 +11,9 @@ Gem::Specification.new do |spec|
   spec.license     = 'MIT'
   spec.metadata    = {}
 
-  spec.add_development_dependency "bundler", "~> 1.16"
-  spec.add_development_dependency "rake", "~> 12.3"
-  spec.add_runtime_dependency "jekyll", "~> 3.8"
+  spec.add_development_dependency "bundler", "~> 2.1"
+  spec.add_development_dependency "rake", "~> 13.0"
+  spec.add_runtime_dependency "jekyll", "~> 4.1"
   spec.add_runtime_dependency "jekyll-paginate", "~> 1.1"
+  spec.add_runtime_dependency "kramdown-parser-gfm", "~> 1.1"
 end