diff --git a/app/models/custom_value.rb b/app/models/custom_value.rb
index 6c68483..6d4af17 100644
--- a/app/models/custom_value.rb
+++ b/app/models/custom_value.rb
@@ -19,6 +19,8 @@ class CustomValue < ActiveRecord::Base
   belongs_to :custom_field
   belongs_to :customized, :polymorphic => true
 
+  validate :validate_custom_value
+
   def after_initialize
     if new_record? && custom_field && (customized_type.blank? || (customized && customized.new_record?))
       self.value ||= custom_field.default_value
@@ -47,7 +49,7 @@ class CustomValue < ActiveRecord::Base
   end
 
 protected
-  def validate
+  def validate_custom_value
     if value.blank?
       errors.add(:value, :blank) if custom_field.is_required? and value.blank?
     else