diff --git a/lib/active_model/serializer/reflection.rb b/lib/active_model/serializer/reflection.rb
index 96cca0be..3e476484 100644
--- a/lib/active_model/serializer/reflection.rb
+++ b/lib/active_model/serializer/reflection.rb
@@ -1,4 +1,5 @@
 require 'active_model/serializer/field'
+require 'active_model/serializer/association'
 
 module ActiveModel
   class Serializer