diff --git a/vendor/plugins/action_tracker/lib/action_tracker_model.rb b/vendor/plugins/action_tracker/lib/action_tracker_model.rb
index 4ce5097..89a5c28 100644
--- a/vendor/plugins/action_tracker/lib/action_tracker_model.rb
+++ b/vendor/plugins/action_tracker/lib/action_tracker_model.rb
@@ -12,6 +12,11 @@ module ActionTracker
 
     validates_presence_of :verb
     validates_presence_of :user
+    validate :user_existence
+
+    def user_existence
+      errors.add(:user, "user doesn't exists") if user && !user.class.exists?(user)
+    end
 
     alias_method :subject, :user
 
diff --git a/vendor/plugins/action_tracker/test/action_tracker_model_test.rb b/vendor/plugins/action_tracker/test/action_tracker_model_test.rb
index bf88d06..01af3d2 100644
--- a/vendor/plugins/action_tracker/test/action_tracker_model_test.rb
+++ b/vendor/plugins/action_tracker/test/action_tracker_model_test.rb
@@ -67,9 +67,32 @@ class ActionTrackerModelTest < ActiveSupport::TestCase
     end
   end
 
+  def test_user_is_mandatory
+    ta = ActionTracker::Record.new :user_type => 'SomeModel', :verb => :some_verb
+    ta.valid?
+    assert ta.errors.on(:user)
+    assert_raise ActiveRecord::RecordInvalid do
+      ta.save!
+    end
+
+    ta = ActionTracker::Record.new :user_id => 2, :verb => :some_verb
+    ta.valid?
+    assert ta.errors.on(:user)
+    assert_raise ActiveRecord::RecordInvalid do
+      ta.save!
+    end
+  end
+
   def test_user_exists_indeed
-    ta = ActionTracker::Record.new(:user_id => -1, :user_type => "SomeModel", :verb => :some_verb)
-    assert !ta.valid?
+    ta = ActionTracker::Record.new(:verb => :some_verb)
+    ta.valid?
+    assert ta.errors.on(:user)
+    user = SomeModel.create!
+    ta.user = user
+    assert ta.valid?
+    user.destroy
+    ta.valid?
+    assert ta.errors.on(:user)
   end
 
   def test_verb_must_be_declared_previously
@@ -333,24 +356,4 @@ class ActionTrackerModelTest < ActiveSupport::TestCase
     assert_equal(["foo 1", "bar 2"], t.collect_group_with_index(:test){|x, i| "#{x} #{i+1}" })
   end
 
-  def test_user_id_is_mandatory
-    ActionTrackerConfig.verbs = { :some => { :description => "Some" } }
-    ta = ActionTracker::Record.new :user_type => 'SomeModel', :verb => :some
-    ta.valid?
-    assert ta.errors.on(:user_id)
-    assert_raise ActiveRecord::RecordInvalid do
-      ta.save!
-    end
-  end
-
-  def test_user_type_is_mandatory
-    ActionTrackerConfig.verbs = { :some => { :description => "Some" } }
-    ta = ActionTracker::Record.new :user_id => 2, :verb => :some
-    ta.valid?
-    assert ta.errors.on(:user_type)
-    assert_raise ActiveRecord::RecordInvalid do
-      ta.save!
-    end
-  end
-
 end
--
libgit2 0.21.2