diff --git a/test/ruby/test_refinement.rb b/test/ruby/test_refinement.rb
index b386c3a8d7..50f0333c2c 100644
--- a/test/ruby/test_refinement.rb
+++ b/test/ruby/test_refinement.rb
@@ -2490,7 +2490,7 @@ class TestRefinement < Test::Unit::TestCase
 
   def test_defining_after_cached
     klass = Class.new
-    refinement = Module.new { refine(klass) { def foo; end } }
+    _refinement = Module.new { refine(klass) { def foo; end } }
     klass.new.foo rescue nil # cache the refinement method entry
     klass.define_method(:foo) { 42 }
     assert_equal(42, klass.new.foo)