diff --git a/app/models/project.rb b/app/models/project.rb
index 082e83f55..20557b759 100644
--- a/app/models/project.rb
+++ b/app/models/project.rb
@@ -626,12 +626,11 @@ class Project < ActiveRecord::Base
   # Returns the users that should be notified on project events
   def notified_users
     # TODO: User part should be extracted to User#notify_about?
-    users =
-      members.preload(:principal).select do |m|
-        m.principal.present? &&
-         (m.mail_notification? || m.principal.mail_notification == 'all')
-      end
-    users.collect {|m| m.principal}
+    subquery =
+      members.select(:user_id)
+      .where.associated(:principal)
+      .where('members.mail_notification = ? OR users.mail_notification = ?', true, 'all')
+    User.where(id: subquery)
   end
 
   # Returns a scope of all custom fields enabled for project issues