diff --git a/.docker/entrypoint/Gemfile b/.docker/entrypoint/Gemfile
index bb659519..08e2961c 100644
--- a/.docker/entrypoint/Gemfile
+++ b/.docker/entrypoint/Gemfile
@@ -14,7 +14,7 @@ gem 'rouge', '~> 3'
 group :development, :test do
   gem 'codecov', '>= 0.6'
   gem 'diffy', '~> 3'
-  gem 'html-proofer', '~> 3'
+  gem 'html-proofer', '~> 4'
   gem 'html-proofer-unrendered-markdown', '>= 0.1'
   gem 'its', '>= 0.2'
   gem 'rake', '~> 13'