diff --git a/app/models/user.rb b/app/models/user.rb
index b5bb6ae..76e9bea 100644
--- a/app/models/user.rb
+++ b/app/models/user.rb
@@ -368,7 +368,7 @@ class User < Principal
 
   def notified_project_ids=(ids)
     @notified_projects_ids_changed = true
-    @notified_projects_ids = ids
+    @notified_projects_ids = ids.map(&:to_i).uniq.select {|n| n > 0}
   end
 
   # Updates per project notifications (after_save callback)
diff --git a/test/unit/user_test.rb b/test/unit/user_test.rb
index df0e79f..bf78420 100644
--- a/test/unit/user_test.rb
+++ b/test/unit/user_test.rb
@@ -948,6 +948,11 @@ class UserTest < ActiveSupport::TestCase
     assert_equal 6, User.valid_notification_options(User.find(2)).size
   end
 
+  def test_notified_project_ids_setter_should_coerce_to_unique_integer_array
+    @jsmith.notified_project_ids = ["1", "123", "2u", "wrong", "12", 6, 12, -35, ""]
+    assert_equal [1, 123, 2, 12, 6], @jsmith.notified_projects_ids
+  end
+
   def test_mail_notification_all
     @jsmith.mail_notification = 'all'
     @jsmith.notified_project_ids = []