diff --git a/book/scripts/Gemfile b/book/scripts/Gemfile
index b6ad7dc6a..433c50155 100644
--- a/book/scripts/Gemfile
+++ b/book/scripts/Gemfile
@@ -4,4 +4,4 @@ source "https://rubygems.org"
 
 git_source(:github) {|repo_name| "https://github.com/#{repo_name}" }
 
-gem 'commonmarker', "0.18.2"
+gem 'commonmarker', "0.23.10"