diff --git a/Assistant/WebApp/Notifications.hs b/Assistant/WebApp/Notifications.hs
index f5b2d7ccdb..5eb2283344 100644
--- a/Assistant/WebApp/Notifications.hs
+++ b/Assistant/WebApp/Notifications.hs
@@ -5,7 +5,7 @@
  - Licensed under the GNU AGPL version 3 or higher.
  -}
 
-{-# LANGUAGE TypeFamilies, QuasiQuotes, MultiParamTypeClasses, TemplateHaskell, OverloadedStrings, RankNTypes #-}
+{-# LANGUAGE CPP, TypeFamilies, QuasiQuotes, MultiParamTypeClasses, TemplateHaskell, OverloadedStrings, RankNTypes #-}
 
 module Assistant.WebApp.Notifications where
 
@@ -20,7 +20,9 @@ import Utility.Yesod
 import Yesod
 import Data.Text (Text)
 import qualified Data.Text as T
+#ifndef WITH_OLD_YESOD
 import qualified Data.Aeson.Types as Aeson
+#endif
 
 {- Add to any widget to make it auto-update using long polling.
  -