diff --git a/lib/asciidoctor/foodogsquared-extensions.rb b/lib/asciidoctor/foodogsquared-extensions.rb
index af6de49..73dc9e4 100644
--- a/lib/asciidoctor/foodogsquared-extensions.rb
+++ b/lib/asciidoctor/foodogsquared-extensions.rb
@@ -2,6 +2,9 @@
 
 require 'asciidoctor'
 require 'asciidoctor/extensions'
+
+require_relative 'helpers'
+
 require_relative 'man-inline-macro/extension'
 require_relative 'swhid-inline-macro/extension'
 require_relative 'swhid-include-processor/extension'
diff --git a/lib/asciidoctor/helpers.rb b/lib/asciidoctor/helpers.rb
new file mode 100644
index 0000000..e2e7351
--- /dev/null
+++ b/lib/asciidoctor/helpers.rb
@@ -0,0 +1,10 @@
+# frozen_string_literal: true
+
+# Code copied from https://gist.github.com/komasaru/b3f22d5bcb8555deea1707b84d294045.
+class String
+  def to_snake
+    self.gsub(/([A-Z]+)([A-Z][a-z])/, '\1_\2')
+        .gsub(/([a-z\d])([A-Z])/, '\1_\2')
+        .downcase
+  end
+end