diff --git a/activesupport/test/array_inquirer_test.rb b/activesupport/test/array_inquirer_test.rb
index 488e0d34a9..b25e5cca86 100644
--- a/activesupport/test/array_inquirer_test.rb
+++ b/activesupport/test/array_inquirer_test.rb
@@ -1,4 +1,5 @@
 require 'abstract_unit'
+require 'active_support/core_ext/array'
 
 class ArrayInquirerTest < ActiveSupport::TestCase
   def setup