diff --git a/app/models/comment.rb b/app/models/comment.rb
index b6fe41e..200b1f1 100644
--- a/app/models/comment.rb
+++ b/app/models/comment.rb
@@ -213,7 +213,7 @@ class Comment < ActiveRecord::Base
   end
 
   def archived?
-    self.article.archived?
+    self.article.archived? if self.article.present? && self.article.respond_to?(:archived?)
   end
 
   protected
diff --git a/lib/noosfero/vote_ext.rb b/lib/noosfero/vote_ext.rb
index be349ca..26f7857 100644
--- a/lib/noosfero/vote_ext.rb
+++ b/lib/noosfero/vote_ext.rb
@@ -8,4 +8,15 @@ class Vote
     voter.present?
   end
 
+  validate :verify_target_archived
+
+  def verify_target_archived
+    if voteable.kind_of?(Article) || voteable.kind_of?(Comment)
+      if voteable.archived?
+        errors.add(:base, _("The target is achived and can't accept votes"))
+        false
+      end
+    end
+  end
+
 end
diff --git a/plugins/vote/lib/ext/vote.rb b/plugins/vote/lib/ext/vote.rb
deleted file mode 100644
index 0b5729e..0000000
--- a/plugins/vote/lib/ext/vote.rb
+++ /dev/null
@@ -1,18 +0,0 @@
-require_dependency 'models/vote'
-
-class Vote
-
-  validate :verify_target_archived
-
-  def verify_target_archived
-
-    if voteable.kind_of?(Article) || voteable.kind_of?(Comment)
-      if voteable.archived?
-        errors.add(:base, _("The target is achived and can't accept votes"))
-        false
-      end
-    end
-    
-  end
-
-end
--
libgit2 0.21.2