diff --git a/.gitlab-ci.yml b/.gitlab-ci.yml
index abadf5b..80822de 100644
--- a/.gitlab-ci.yml
+++ b/.gitlab-ci.yml
@@ -13,7 +13,7 @@ variables:
   LC_ALL: C.UTF-8
 
 before_script:
-  - gem install bundler
+  - gem install bundler -v 2.4.22
   - bundle install
 
 pages:
diff --git a/Gemfile b/Gemfile
index 9ffec38..df61ca4 100644
--- a/Gemfile
+++ b/Gemfile
@@ -1,11 +1,11 @@
 source "https://rubygems.org"
 gem "jekyll", "~> 3.9.3"
 group :jekyll_plugins do
-  gem "jekyll-gist"
-  gem "jekyll-coffeescript"
+  gem "jekyll-gist", "~> 1.5.0"
+  gem "jekyll-coffeescript", "~> 1.1.1"
   gem "jekyll-assets"
-  gem "jekyll-sitemap"
-  gem "jekyll-feed"
+  gem "jekyll-sitemap", "~> 1.4.0"
+  gem "jekyll-feed", "~> 0.15.1"
   gem "jekyll-theme-minimal"
-  gem "jekyll-paginate"
+  gem "jekyll-paginate", "~> 1.1.0"
 end