diff --git a/2022/05-gencant/Rakefile b/2022/05-gencant/Rakefile
index 8085388..d6eafb8 100644
--- a/2022/05-gencant/Rakefile
+++ b/2022/05-gencant/Rakefile
@@ -1,7 +1,38 @@
 require 'squib'
 
-task default: [:deck]
+module OS
+  def OS.windows?
+    (/cygwin|mswin|mingw|bccwin|wince|emx/ =~ RUBY_PLATFORM) != nil
+  end
+
+  def OS.mac?
+   (/darwin/ =~ RUBY_PLATFORM) != nil
+  end
+
+  def OS.unix?
+    !OS.windows?
+  end
+
+  def OS.linux?
+    OS.unix? and not OS.mac?
+  end
+
+  def OS.jruby?
+    RUBY_ENGINE == 'jruby'
+  end
+end
+
+task default: [:deck, :rules]
 
 task :deck do
   load 'deck.rb'
 end
+
+desc 'Build the rules PDF'
+task rules: "_output/RULES.pdf"
+
+file "_output/RULES.pdf" => ["Rules.md", "_output"] do |t|
+  respaths = [".", "docs/"]
+  if OS.windows? then sep = ";" else sep = ":" end
+  sh "pandoc", "-o", t.name, t.source, "--resource-path=#{respaths.join(sep)}"
+end
\ No newline at end of file