diff --git a/Gemfile b/Gemfile
old mode 100755
new mode 100644
index 630744d..f5654da
--- a/Gemfile
+++ b/Gemfile
@@ -1,5 +1,5 @@
 source "https://rubygems.org"
 
 gem 'github-pages'
-gem 'html-proofer'
+gem 'html-proofer', '>= 3.15.0'
 gem 'tzinfo-data', platforms: [:mingw, :mswin, :x64_mingw]