diff --git a/Gemfile b/Gemfile
index 405429c61..3d44e4cbc 100644
--- a/Gemfile
+++ b/Gemfile
@@ -13,4 +13,4 @@ gem 'coderay', '1.1.3'
 gem 'pygments.rb', '2.0.0'
 gem 'thread_safe', '0.3.6'
 gem 'epubcheck-ruby', '4.2.4.0'
-gem 'html-proofer', '3.18.5'
+gem 'html-proofer', '4.4.3'