diff --git a/test/fiddle/test_closure.rb b/test/fiddle/test_closure.rb
index ae343460f2..70005466ad 100644
--- a/test/fiddle/test_closure.rb
+++ b/test/fiddle/test_closure.rb
@@ -45,5 +45,12 @@ module Fiddle
       func = Function.new(cb, [TYPE_INT], TYPE_INT)
       assert_equal 11, func.call(11)
     end
+
+    def test_memsize
+      require 'objspace'
+      bug = '[ruby-dev:42480]'
+      n = 10000
+      assert_equal(n, n.times {ObjectSpace.memsize_of(Closure.allocate)}, bug)
+    end
   end
 end