diff --git a/activesupport/lib/active_support/json/encoding.rb b/activesupport/lib/active_support/json/encoding.rb
index 5441145dfd..5fefe5b88b 100644
--- a/activesupport/lib/active_support/json/encoding.rb
+++ b/activesupport/lib/active_support/json/encoding.rb
@@ -10,7 +10,7 @@ module ActiveSupport
         raise CircularReferenceError, 'object references itself'
       end
       seen << value
-      value.send(:rails_to_json, options, seen)
+      value.__send__(:rails_to_json, options, seen)
     ensure
       seen.pop
     end