diff --git a/Gemfile b/Gemfile
index 3a09b0367..438883712 100644
--- a/Gemfile
+++ b/Gemfile
@@ -8,10 +8,10 @@ source "https://rubygems.org"
 #
 # This will help ensure the proper Jekyll version is running.
 # Happy Jekylling!
-gem "jekyll", "~> 3.8.3"
+gem "jekyll", "~> 4.3.3"
 
 # This is the default theme for new Jekyll sites. You may change this to anything you like.
-gem "minima", "~> 2.0"
+gem "minima", "~> 2.5"
 
 # If you want to use GitHub Pages, remove the "gem "jekyll"" above and
 # uncomment the line below. To upgrade, run `bundle update github-pages`.
@@ -19,12 +19,22 @@ gem "minima", "~> 2.0"
 
 # If you have any plugins, put them here!
 group :jekyll_plugins do
-  gem "jekyll-feed", "~> 0.6"
+  gem "jekyll-feed", "~> 0.12"
+end
+
+# Windows and JRuby does not include zoneinfo files, so bundle the tzinfo-data gem
+# and associated library.
+platforms :mingw, :x64_mingw, :mswin, :jruby do
+  gem "tzinfo", ">= 1", "< 3"
+  gem "tzinfo-data"
 end
 
-# Windows does not include zoneinfo files, so bundle the tzinfo-data gem
-gem "tzinfo-data", platforms: [:mingw, :mswin, :x64_mingw, :jruby]
 
 # Performance-booster for watching directories on Windows
-gem "wdm", "~> 0.1.0" if Gem.win_platform?
+gem "wdm", "~> 0.1.1", :platforms => [:mingw, :x64_mingw, :mswin]
+
+# Lock `http_parser.rb` gem to `v0.6.x` on JRuby builds since newer versions of the gem
+# do not have a Java counterpart.
+gem "http_parser.rb", "~> 0.6.0", :platforms => [:jruby]
+