diff --git a/asciidoctorj-pdf/gradle.properties b/asciidoctorj-pdf/gradle.properties
index 29fdd9b..4f1984e 100644
--- a/asciidoctorj-pdf/gradle.properties
+++ b/asciidoctorj-pdf/gradle.properties
@@ -1,4 +1,4 @@
 properName=AsciidoctorJ PDF
 description=AsciidoctorJ PDF bundles the Asciidoctor PDF RubyGem (asciidoctor-pdf) so it can be loaded into the JVM using JRuby.
-version=2.3.12
+version=2.3.13
 gem_name=asciidoctor-pdf
diff --git a/build.gradle b/build.gradle
index 51ad22c..c594de6 100644
--- a/build.gradle
+++ b/build.gradle
@@ -38,7 +38,7 @@ ext {
 
   // gem versions
   asciidoctorJVersion = project.hasProperty('asciidoctorJVersion') ? project.asciidoctorJVersion : '2.5.7'
-  asciidoctorPdfGemVersion = project.hasProperty('asciidoctorPdfGemVersion') ? project.asciidoctorPdfGemVersion : '2.3.12'
+  asciidoctorPdfGemVersion = project.hasProperty('asciidoctorPdfGemVersion') ? project.asciidoctorPdfGemVersion : '2.3.13'
 
   addressableVersion = '2.8.0'
   concurrentRubyVersion = '1.1.7'
diff --git a/gradle.properties b/gradle.properties
index c41e802..eb05369 100644
--- a/gradle.properties
+++ b/gradle.properties
@@ -1,4 +1,4 @@
-version=2.3.12
+version=2.3.13
 sourceCompatibility=1.8
 targetCompatibility=1.8