diff --git a/test/ruby/test_optimization.rb b/test/ruby/test_optimization.rb
index dc542b644e..e8b4f92d92 100644
--- a/test/ruby/test_optimization.rb
+++ b/test/ruby/test_optimization.rb
@@ -689,7 +689,7 @@ class TestRubyOptimization < Test::Unit::TestCase
   end
 
   def test_clear_unreachable_keyword_args
-    assert_separately [], <<-END
+    assert_separately [], <<-END, timeout: 15
       script =  <<-EOS
         if true
         else