diff --git a/Gemfile b/Gemfile
index b3c29b7a..d2bd2f91 100644
--- a/Gemfile
+++ b/Gemfile
@@ -4,5 +4,6 @@ gemspec
 gem "jekyll", ENV["JEKYLL_VERSION"] if ENV["JEKYLL_VERSION"]
 if ENV["JEKYLL_VERSION"] == "< 4.0"
   gem "base64", "~> 0.2"
+  gem "bigdecimal"
   gem "kramdown-parser-gfm", "~> 1.0"
 end