diff --git a/lib/active_model/serializer.rb b/lib/active_model/serializer.rb
index 6e00c2db..5fae89bc 100644
--- a/lib/active_model/serializer.rb
+++ b/lib/active_model/serializer.rb
@@ -1,4 +1,6 @@
 require 'thread_safe'
+require_relative 'serializer/configuration'
+require_relative 'serializer/associations'
 
 module ActiveModel
   class Serializer