diff --git a/Gemfile b/Gemfile
index dd6254f..bbea1bf 100644
--- a/Gemfile
+++ b/Gemfile
@@ -11,7 +11,7 @@ group :jekyll_plugins do
 end
 
 group :test do
-  gem "html-proofer"
+  gem "html-proofer", "~> 3.16.0"
 end
 
 # Windows and JRuby does not include zoneinfo files, so bundle the tzinfo-data gem