diff --git a/lib/zip/entry_set.rb b/lib/zip/entry_set.rb
index 59d34c7..2e7ce39 100755
--- a/lib/zip/entry_set.rb
+++ b/lib/zip/entry_set.rb
@@ -49,7 +49,7 @@ module Zip
 
     # deep clone
     def dup
-      EntrySet.new(@entry_set.map { |_key, value| value.dup })
+      EntrySet.new(@entry_set.values.map(&:dup))
     end
 
     def ==(other)