diff --git a/activesupport/lib/active_support/core_ext/class/delegating_attributes.rb b/activesupport/lib/active_support/core_ext/class/delegating_attributes.rb
index 301c09fc73..72e0eefb0a 100644
--- a/activesupport/lib/active_support/core_ext/class/delegating_attributes.rb
+++ b/activesupport/lib/active_support/core_ext/class/delegating_attributes.rb
@@ -1,5 +1,4 @@
 require 'active_support/core_ext/object/blank'
-require 'active_support/core_ext/object/duplicable'
 require 'active_support/core_ext/array/extract_options'
 
 class Class