diff --git a/vendor/plugins/inverse_captcha/lib/inverse_captcha.rb b/vendor/plugins/inverse_captcha/lib/inverse_captcha.rb
index b296571..8f7a341 100644
--- a/vendor/plugins/inverse_captcha/lib/inverse_captcha.rb
+++ b/vendor/plugins/inverse_captcha/lib/inverse_captcha.rb
@@ -2,9 +2,9 @@ module InverseCaptcha
 
   module ClassMethods
     def inverse_captcha(opt = {})
-      InverseCaptcha.const_set("ICAPTCHA_FIELD", opt[:field])
-      InverseCaptcha.const_set("ICAPTCHA_LABEL", opt[:label] || N_("Don't fill this field"))
-      InverseCaptcha.const_set("ICAPTCHA_STYLECLASS", opt[:class] || 'ghost')
+      InverseCaptcha.const_set("ICAPTCHA_FIELD", opt[:field]) unless InverseCaptcha.const_defined? "ICAPTCHA_FIELD"
+      InverseCaptcha.const_set("ICAPTCHA_LABEL", opt[:label] || N_("Don't fill this field")) unless InverseCaptcha.const_defined? "ICAPTCHA_LABEL"
+      InverseCaptcha.const_set("ICAPTCHA_STYLECLASS", opt[:class] || 'ghost') unless InverseCaptcha.const_defined? "ICAPTCHA_STYLECLASS"
       self.send(:include, InverseCaptcha)
     end
   end
--
libgit2 0.21.2