diff --git a/Gemfile b/Gemfile
index 4ecffb4..33dd0ac 100644
--- a/Gemfile
+++ b/Gemfile
@@ -1,7 +1,7 @@
 source 'https://rubygems.org'
 
 gem 'rake'
-gem 'asciidoctor', '1.5.6.1'
+gem 'asciidoctor', '1.5.8'
 
 gem 'json'
 gem 'awesome_print'
diff --git a/Gemfile.lock b/Gemfile.lock
index c558283..7721ff1 100644
--- a/Gemfile.lock
+++ b/Gemfile.lock
@@ -14,7 +14,7 @@ GEM
     addressable (2.8.0)
       public_suffix (>= 2.0.2, < 5.0)
     afm (0.2.2)
-    asciidoctor (1.5.6.1)
+    asciidoctor (1.5.8)
     asciidoctor-pdf (1.5.0.alpha.16)
       asciidoctor (>= 1.5.0)
       prawn (>= 1.3.0, < 2.3.0)
@@ -79,7 +79,7 @@ PLATFORMS
   ruby
 
 DEPENDENCIES
-  asciidoctor (= 1.5.6.1)
+  asciidoctor (= 1.5.8)
   asciidoctor-epub3!
   asciidoctor-pdf (= 1.5.0.alpha.16)
   awesome_print