diff --git a/lib/sidekiq/processor.rb b/lib/sidekiq/processor.rb
index d267b97d..28363aed 100644
--- a/lib/sidekiq/processor.rb
+++ b/lib/sidekiq/processor.rb
@@ -15,7 +15,7 @@ module Sidekiq
     include Util
     include Celluloid
 
-#    exclusive :process
+    task_class Celluloid::TaskThread
 
     def self.default_middleware
       Middleware::Chain.new do |m|