diff --git a/Casks/pdfpen.rb b/Casks/pdfpen.rb
index bf1be6c0b..fe167e300 100644
--- a/Casks/pdfpen.rb
+++ b/Casks/pdfpen.rb
@@ -4,7 +4,7 @@ cask :v1 => 'pdfpen' do
 
   url 'http://dl.smilesoftware.com/com.smileonmymac.PDFpen/PDFpen.zip'
   homepage 'http://smilesoftware.com/PDFpen/index.html'
-  license :unknown    # todo: improve this machine-generated value
+  license :unknown    # todo: change license and remove this comment; ':unknown' is a machine-generated placeholder
 
   app 'PDFpen.app'
 end