1 files changed, 7 insertions, 1 deletions
diff --git a/activemodel/lib/active_model/validations/confirmation.rb b/activemodel/lib/active_model/validations/confirmation.rb
index 1d85378892..b0542661af 100644
--- a/activemodel/lib/active_model/validations/confirmation.rb
+++ b/activemodel/lib/active_model/validations/confirmation.rb
@@ -2,6 +2,11 @@ module ActiveModel
 
   module Validations
     class ConfirmationValidator < EachValidator # :nodoc:
+      def initialize(options)
+        super
+        setup!(options[:class])
+      end
+
       def validate_each(record, attribute, value)
         if (confirmed = record.send("#{attribute}_confirmation")) && (value != confirmed)
           human_attribute_name = record.class.human_attribute_name(attribute)
@@ -9,7 +14,8 @@ module ActiveModel
         end
       end
 
-      def setup(klass)
+      private
+      def setup!(klass)
         klass.send(:attr_reader, *attributes.map do |attribute|
           :"#{attribute}_confirmation" unless klass.method_defined?(:"#{attribute}_confirmation")
         end.compact)