diff --git a/activesupport/test/core_ext/kernel/concern_test.rb b/activesupport/test/core_ext/kernel/concern_test.rb
index 9b1fdda3b0ef0ee45cdcd2128c8b961c3f251ad0..478a00d2d20846f277f630da15c855b377dc7265 100644
--- a/activesupport/test/core_ext/kernel/concern_test.rb
+++ b/activesupport/test/core_ext/kernel/concern_test.rb
@@ -6,7 +6,8 @@ def test_may_be_defined_at_toplevel
     mod = ::TOPLEVEL_BINDING.eval 'concern(:ToplevelConcern) { }'
     assert_equal mod, ::ToplevelConcern
     assert_kind_of ActiveSupport::Concern, ::ToplevelConcern
-    assert !Object.ancestors.include?(::ToplevelConcern), mod.ancestors.inspect
+    assert_not Object.ancestors.include?(::ToplevelConcern), mod.ancestors.inspect
+  ensure
     Object.send :remove_const, :ToplevelConcern
   end
 end