diff --git a/src/Handler/Corrections.hs b/src/Handler/Corrections.hs
index 4915659ad..f1d5085a5 100644
--- a/src/Handler/Corrections.hs
+++ b/src/Handler/Corrections.hs
@@ -1156,7 +1156,7 @@ assignHandler tid ssh csh cid assignSids = do
             (\acc (E.Value sheetCorrectorSheet, Entity uid user) ->
                 let shn = sheetName $ sheets ! sheetCorrectorSheet
                     scr = SheetCorrector uid sheetCorrectorSheet mempty CorrectorExcused
-                in  Map.insertWith (\new old -> old) uid (user, Map.singleton shn scr) acc -- keep already known correctors unchanged
+                in  Map.insertWith (\_new old -> old) uid (user, Map.singleton shn scr) acc -- keep already known correctors unchanged
             )
 
       submissions <- E.select . E.from $ \submission -> do