diff --git a/ext/tk/lib/tkextlib/tkDND/tkdnd.rb b/ext/tk/lib/tkextlib/tkDND/tkdnd.rb
index 97cdfc7f1c..38e05ce775 100644
--- a/ext/tk/lib/tkextlib/tkDND/tkdnd.rb
+++ b/ext/tk/lib/tkextlib/tkDND/tkdnd.rb
@@ -158,7 +158,7 @@ module Tk
           cmd = Proc.new
         end
 
-        args = [None] if args.empty
+        args = [TkComm::None] if args.empty?
 
         tk_call('dnd', 'bindsource', @path, type, cmd, *args)
         self