diff --git a/src/Handler/Course.hs b/src/Handler/Course.hs
index 584d91e02..5852409c6 100644
--- a/src/Handler/Course.hs
+++ b/src/Handler/Course.hs
@@ -892,8 +892,15 @@ postCUserR tid ssh csh uCId = do
   -- De-/Register Button for Lecturer
   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 $ \(mbfeatures, _secretCorrect) ->
-    error "TODO: change registration"
+  formResult registerRes $ \(mbSfId, _secretCorrect) -> if -- lecturers need no secret verification
+      -- | isRegistered -> do
+      | 1 + 2 < 42 -> do
+          runDB $ deleteBy $ UniqueParticipant uid cid
+          addMessageI Info MsgCourseDeregisterOk
+      | otherwise -> do
+          actTime <- liftIO getCurrentTime
+          regOk <- runDB $ insertUnique $ CourseParticipant cid uid actTime mbSfId
+          when (isJust regOk) $ addMessageI Success MsgCourseRegisterOk
   -- generate output
   let headingLong  = [whamlet|^{nameWidget userDisplayName userSurname} - _{MsgCourseMemberOf} #{csh} #{display tid}|]
       headingShort = prependCourseTitle tid ssh csh $ SomeMessage userDisplayName