diff --git a/src/Foundation.hs b/src/Foundation.hs
index ee0c578d5..239cc33cc 100644
--- a/src/Foundation.hs
+++ b/src/Foundation.hs
@@ -427,7 +427,8 @@ knownTags = Map.fromList -- should not throw exceptions, i.e. no getBy404 or req
         cTime <- liftIO getCurrentTime
         let
           visible = NTop sheetVisibleFrom <= NTop (Just cTime)
-          active = sheetActiveFrom <= cTime && cTime <= sheetActiveTo
+          active  = sheetActiveFrom <= cTime && cTime <= sheetActiveTo
+          marking = cTime > sheetActiveTo
 
         guard visible
 
@@ -436,7 +437,7 @@ knownTags = Map.fromList -- should not throw exceptions, i.e. no getBy404 or req
           SFileR SheetHint     _    -> guard $ maybe False (<= cTime) sheetHintFrom
           SFileR SheetSolution _    -> guard $ maybe False (<= cTime) sheetSolutionFrom
           SubmissionNewR            -> guard   active
-          SubmissionR _ SAssignR    -> guard $ not active -- Correctors can only be assigned when the Sheet is inactive, since submissions are subject to change
+          SubmissionR _ SAssignR    -> guard $ marking -- Correctors can only be assigned when the Sheet is inactive, since submissions are subject to change
           SubmissionR _ _           -> guard   active
           _                         -> return ()