diff --git a/spec/rdoc_generator_markup_spec.rb b/spec/rdoc_generator_markup_spec.rb
index 2b2a2eb0..5d44bb8e 100644
--- a/spec/rdoc_generator_markup_spec.rb
+++ b/spec/rdoc_generator_markup_spec.rb
@@ -18,7 +18,7 @@
 
     it "should ignore lower level titles" do
       @module.comment = RDoc::Comment.new '== Some Title'
-      _(@module.comment_title).must_equal nil
+      _(@module.comment_title).must_be_nil
     end
   end