diff --git a/activesupport/test/core_ext/object/duplicable_test.rb b/activesupport/test/core_ext/object/duplicable_test.rb
index c2d7c15..2e3b185 100644
--- a/activesupport/test/core_ext/object/duplicable_test.rb
+++ b/activesupport/test/core_ext/object/duplicable_test.rb
@@ -5,8 +5,8 @@
 
 class DuplicableTest < ActiveSupport::TestCase
   if RUBY_VERSION >= "2.4.0"
-    RAISE_DUP = [method(:puts)]
-    ALLOW_DUP = ["1", Object.new, /foo/, [], {}, Time.now, Class.new, Module.new, BigDecimal.new("4.56"), nil, false, true, :symbol, 1, 2.3]
+    RAISE_DUP = [method(:puts), 'symbol_from_string'.to_sym]
+    ALLOW_DUP = ["1", Object.new, /foo/, [], {}, Time.now, Class.new, Module.new, BigDecimal.new("4.56"), nil, false, true, 1, 2.3]
   else
     RAISE_DUP = [nil, false, true, :symbol, 1, 2.3, method(:puts)]
     ALLOW_DUP = ["1", Object.new, /foo/, [], {}, Time.now, Class.new, Module.new, BigDecimal.new("4.56")]