diff --git a/Gemfile b/Gemfile
index 78ccf7e3..a1a0ab81 100644
--- a/Gemfile
+++ b/Gemfile
@@ -12,6 +12,6 @@ gem 'asciidoctor-pdf', '2.1.1'
 gem 'coderay', '1.1.3'
 gem 'pygments.rb', '2.3.0'
 gem 'thread_safe', '0.3.6'
-gem 'html-proofer', '3.19.4'
+gem 'html-proofer', '5.0.7'
 gem 'epubcheck-ruby', '4.2.6.0'
 gem 'kindlegen', '3.1.1'