diff --git a/Gemfile b/Gemfile
index aa3c7a6..04970e1 100644
--- a/Gemfile
+++ b/Gemfile
@@ -14,4 +14,4 @@ gem 'coderay', '1.1.3'
 gem 'pygments.rb', '5.0.0'
 gem 'thread_safe', '0.3.6'
 gem 'epubcheck-ruby', '5.3.0.0'
-gem 'html-proofer', '5.2.2'
+gem 'html-proofer', '5.2.3'