diff --git a/Gemfile b/Gemfile
index b9ce05859..8bac1ca4a 100644
--- a/Gemfile
+++ b/Gemfile
@@ -8,7 +8,7 @@ gem 'awesome_print', '1.9.2'
 
 gem 'asciidoctor-fb2', '0.7.0'
 gem 'asciidoctor-epub3', '2.1.3'
-gem 'asciidoctor-pdf', '2.3.17'
+gem 'asciidoctor-pdf', '2.3.18'
 
 gem 'coderay', '1.1.3'
 gem 'pygments.rb', '2.4.1'