diff --git a/app/models/err.rb b/app/models/err.rb
index 55fe50d..1988050 100644
--- a/app/models/err.rb
+++ b/app/models/err.rb
@@ -14,6 +14,7 @@ class Err
 
   belongs_to :problem
   index :problem_id
+  index :klass
 
   has_many :notices, :inverse_of => :err, :dependent => :destroy
 
diff --git a/app/models/notice.rb b/app/models/notice.rb
index e3405bc..0d284c3 100644
--- a/app/models/notice.rb
+++ b/app/models/notice.rb
@@ -13,8 +13,14 @@ class Notice
   field :klass
 
   belongs_to :err
-  index :err_id
   index :created_at
+  index(
+    [
+      [ :err_id, Mongo::ASCENDING ],
+      [ :created_at, Mongo::ASCENDING ],
+      [ :_id, Mongo::ASCENDING ]
+    ]
+  )
 
   after_create :increase_counter_cache, :cache_attributes_on_problem, :unresolve_problem
   after_create :deliver_notification, :if => :should_notify?
--
libgit2 0.21.2