diff --git a/lib/cancan/mongoid_additions.rb b/lib/cancan/mongoid_additions.rb
index 37fd37c..31eb7d6 100644
--- a/lib/cancan/mongoid_additions.rb
+++ b/lib/cancan/mongoid_additions.rb
@@ -86,7 +86,7 @@ module CanCan
         if query.conditions.blank?
           # this query is sure to return no results
           # we need this so there is a Mongoid::Criteria object to return, since an empty array would cause problems
-          where({:_id => {'$exists' => true, '$type' => 2}})  
+          where({:_id => {'$exists' => false, '$type' => 7}})  # type 7 is an ObjectID (default for _id)
         else   
           where(query.conditions)
         end
diff --git a/spec/cancan/mongoid_additions_spec.rb b/spec/cancan/mongoid_additions_spec.rb
index 68df0eb..9f8e423 100644
--- a/spec/cancan/mongoid_additions_spec.rb
+++ b/spec/cancan/mongoid_additions_spec.rb
@@ -51,6 +51,10 @@ describe CanCan::MongoidAdditions do
   end
 
   it "should return [] when no ability is defined so no records are found" do
+    @model_class.create :title  => 'Sir'
+    @model_class.create :title  => 'Lord'
+    @model_class.create :title  => 'Dude'
+      
     @model_class.accessible_by(@ability, :read).should == []
   end