diff --git a/activerecord/lib/active_record/relation/delegation.rb b/activerecord/lib/active_record/relation/delegation.rb
index 50f4d5c7ab..df3ac43b0a 100644
--- a/activerecord/lib/active_record/relation/delegation.rb
+++ b/activerecord/lib/active_record/relation/delegation.rb
@@ -119,6 +119,10 @@ module ActiveRecord
         arel.respond_to?(method, include_private)
     end
 
+    def encode_with(coder)
+      coder.represent_seq(nil, to_a)
+    end
+
     protected
 
     def array_delegable?(method)
diff --git a/activerecord/test/cases/yaml_serialization_test.rb b/activerecord/test/cases/yaml_serialization_test.rb
index 9f1d110ddb..bce59b4fcd 100644
--- a/activerecord/test/cases/yaml_serialization_test.rb
+++ b/activerecord/test/cases/yaml_serialization_test.rb
@@ -1,5 +1,6 @@
 require 'cases/helper'
 require 'models/topic'
+require 'models/reply'
 require 'models/post'
 require 'models/author'