diff --git a/test/fiddle/test_function.rb b/test/fiddle/test_function.rb
index a58d7afcb1..4a6bc6c3d4 100644
--- a/test/fiddle/test_function.rb
+++ b/test/fiddle/test_function.rb
@@ -98,7 +98,7 @@ module Fiddle
     end
 
     def test_no_memory_leak
-      prep = 'r = Fiddle::Function.new(Fiddle.dlopen(nil)["rb_obj_frozen"], [Fiddle::TYPE_UINTPTR_T], Fiddle::TYPE_UINTPTR_T); a = "a"'
+      prep = 'r = Fiddle::Function.new(Fiddle.dlopen(nil)["rb_obj_frozen_p"], [Fiddle::TYPE_UINTPTR_T], Fiddle::TYPE_UINTPTR_T); a = "a"'
       code = 'begin r.call(a); rescue TypeError; end'
       assert_no_memory_leak(%w[-W0 -rfiddle], "#{prep}\n1000.times{#{code}}", "10_000.times {#{code}}", limit: 1.2)
     end