diff --git a/config.ru b/config.ru
index c45449dd03f94959e824e7fbcc43057d7583cc72..e90863a5c21baf365868b4ad325c88cd52338949 100644
--- a/config.ru
+++ b/config.ru
@@ -1,6 +1,6 @@
 # This file is used by Rack-based servers to start the application.
 
-unless defined?(PhusionPassenger)
+if defined?(Unicorn)
   require 'unicorn'
   # Unicorn self-process killer
   require 'unicorn/worker_killer'