diff --git a/Dockerfile b/Dockerfile
index cc95726..0410a8f 100644
--- a/Dockerfile
+++ b/Dockerfile
@@ -5,7 +5,7 @@ ENTRYPOINT [""]
 ENV ASCIIDOCTOR_VERSION=2.0.20
 
 # renovate: datasource=rubygems depName=asciidoctor-pdf
-ENV ASCIIDOCTOR_PDF_VERSION=2.3.12
+ENV ASCIIDOCTOR_PDF_VERSION=2.3.13
 
 # renovate: datasource=rubygems depName=asciidoctor-diagram
 ENV ASCIIDOCTOR_DIAGRAM_VERSION=2.3.0