diff --git a/src/Foundation/Yesod/Middleware.hs b/src/Foundation/Yesod/Middleware.hs
index 95d3629f0..683bb8ab6 100644
--- a/src/Foundation/Yesod/Middleware.hs
+++ b/src/Foundation/Yesod/Middleware.hs
@@ -184,11 +184,9 @@ updateFavourites cData = void . withReaderT projectBackend . runMaybeT $ do
   mcid  <- (for cData $ \(tid, ssh, csh) -> MaybeT . getKeyBy $ TermSchoolCourseShort tid ssh csh) :: MaybeT (SqlPersistT m) (Maybe CourseId)
   User{userMaxFavourites} <- MaybeT $ get uid
 
-  -- TODO optimize for `userMaxFavourites == 0`
-  -- no need to store (upsert?) them, since they will be removed in the pruning step anyway!
-
   -- update Favourites
-  for_ mcid $ \cid ->
+  -- no need to store them with userMaxFavourites==0, since they will be removed in the pruning step anyway!
+  when (userMaxFavourites > 0) $ for_ mcid $ \cid ->
     void . lift $ upsertBy
       (UniqueCourseFavourite uid cid)
       (CourseFavourite uid cid FavouriteVisited now)