diff --git a/app/models/notification.rb b/app/models/notification.rb
index 1e9dfa3dd..0b1829267 100644
--- a/app/models/notification.rb
+++ b/app/models/notification.rb
@@ -9,6 +9,7 @@ class Notification < ActiveRecord::Base
   after_initialize :set_defaults
 
   def mark_as_read
+    raise 'Read notification cannot be marked as read again' if read?
     self.read = true
     save
   end
diff --git a/test/models/notification_test.rb b/test/models/notification_test.rb
index bfd577fb9..3db685e0c 100644
--- a/test/models/notification_test.rb
+++ b/test/models/notification_test.rb
@@ -32,4 +32,11 @@ class NotificationTest < ActiveSupport::TestCase
     @notification.reload
     assert @notification.read?
   end
+
+  def test_read_notification_cannot_be_marked_as_read_again
+    @notification.mark_as_read
+    assert_raises do
+      @notification.mark_as_read
+    end
+  end
 end
\ No newline at end of file