diff --git a/lib/simple_captcha/simple_captcha_data.rb b/lib/simple_captcha/simple_captcha_data.rb
index 8208d10..16940f4 100644
--- a/lib/simple_captcha/simple_captcha_data.rb
+++ b/lib/simple_captcha/simple_captcha_data.rb
@@ -3,6 +3,8 @@ class SimpleCaptchaData < ::ActiveRecord::Base
 
     self.table_name = "simple_captcha_data"
 
+    attr_accessible :key
+
     class << self
       def get_data(key)
         data = where(key: key).first || new(key: key)