diff --git a/src/Handler/Course.hs b/src/Handler/Course.hs
index 5852409c6..cb2bd4b3b 100644
--- a/src/Handler/Course.hs
+++ b/src/Handler/Course.hs
@@ -893,8 +893,7 @@ postCUserR tid ssh csh uCId = do
   mRegAt   <- traverse (formatTime SelFormatDateTime) $ courseParticipantRegistration <$> registration
   ((registerRes,registerView), registerEnctype) <- runFormPost $ registerForm (Just uid) registration Nothing Nothing -- Lecturers are never asked their own register secret
   formResult registerRes $ \(mbSfId, _secretCorrect) -> if -- lecturers need no secret verification
-      -- | isRegistered -> do
-      | 1 + 2 < 42 -> do
+      | isJust registration -> do
           runDB $ deleteBy $ UniqueParticipant uid cid
           addMessageI Info MsgCourseDeregisterOk
       | otherwise -> do