diff --git a/lib/thin/rackup/handler.rb b/lib/thin/rackup/handler.rb
index b66e6ba2..4bb166a0 100644
--- a/lib/thin/rackup/handler.rb
+++ b/lib/thin/rackup/handler.rb
@@ -1,5 +1,7 @@
 # frozen_string_literal: true
 
+require_relative "../server"
+
 module Thin
   module Rackup
     class Handler