diff --git a/test/ruby/test_thread_cv.rb b/test/ruby/test_thread_cv.rb
index 88733419da14fd..8c2800186adddc 100644
--- a/test/ruby/test_thread_cv.rb
+++ b/test/ruby/test_thread_cv.rb
@@ -8,7 +8,7 @@ class TestThreadConditionVariable < Test::Unit::TestCase
 
   def test_initialized
     assert_raise(TypeError) {
-      ConditionVariable.allocate.wait(nil)
+      ConditionVariable.allocate.wait(nil, "")
     }
   end