diff --git a/docs/pom.xml b/docs/pom.xml
index 3a6c86a..9078c81 100644
--- a/docs/pom.xml
+++ b/docs/pom.xml
@@ -16,7 +16,7 @@
 
     <properties>
         <version.asciidoctor-maven-plugin>3.2.0</version.asciidoctor-maven-plugin>
-        <version.org.asciidoctor.asciidoctorj-pdf>2.3.20</version.org.asciidoctor.asciidoctorj-pdf>
+        <version.org.asciidoctor.asciidoctorj-pdf>2.3.21</version.org.asciidoctor.asciidoctorj-pdf>
         <version.org.asciidoctor.asciidoctorj-epub3>2.2.0</version.org.asciidoctor.asciidoctorj-epub3>
     </properties>