diff --git a/Gemfile b/Gemfile
index ed09564..6a9aab2 100644
--- a/Gemfile
+++ b/Gemfile
@@ -8,6 +8,6 @@ group :jekyll_plugins do
   gem "jekyll-asciidoc"
 end
 
-gem 'asciidoctor', '~> 1.5.4'
+gem 'asciidoctor', '~> 1.5.8'
 gem 'coderay', '1.1.1'
 
diff --git a/Gemfile.lock b/Gemfile.lock
index b1a140a..c5078b7 100644
--- a/Gemfile.lock
+++ b/Gemfile.lock
@@ -3,7 +3,7 @@ GEM
   specs:
     addressable (2.5.2)
       public_suffix (>= 2.0.2, < 4.0)
-    asciidoctor (1.5.7.1)
+    asciidoctor (1.5.8)
     coderay (1.1.1)
     colorator (1.1.0)
     concurrent-ruby (1.0.5)
@@ -73,7 +73,7 @@ PLATFORMS
   ruby
 
 DEPENDENCIES
-  asciidoctor (~> 1.5.4)
+  asciidoctor (~> 1.5.8)
   coderay (= 1.1.1)
   jekyll
   jekyll-asciidoc