diff --git a/Gemfile b/Gemfile
index d3c7840..feefa3e 100644
--- a/Gemfile
+++ b/Gemfile
@@ -1,8 +1,8 @@
 
 gem "rake", "~> 13.0"
 
-gem "asciidoctor-pdf", "~> 1.5"
+gem "asciidoctor-pdf", "~> 1.5", ">= 1.5.4"
 
-gem "asciidoctor-diagram", "~> 2.1"
+gem "asciidoctor-diagram", "~> 2.1", ">= 2.1.2"
 
 gem "listen", "~> 3.4"