diff --git a/src/Data/List/Local.hs b/src/Data/List/Local.hs
index 06405e0..e7d5555 100644
--- a/src/Data/List/Local.hs
+++ b/src/Data/List/Local.hs
@@ -37,7 +37,7 @@ import Data.List.NonEmpty (NonEmpty (..), (<|))
 --
 -- >>> groupJusts [Nothing, Nothing, Just 1, Just 4, Nothing, Just 2]
 -- [[1, 4], [2]]
-groupJusts :: [Maybe a] -> [NonEmpty a]
+groupJusts :: Foldable f => f (Maybe a) -> [NonEmpty a]
 groupJusts maybes = prepend $ foldr go (Nothing, []) maybes
     where
     prepend (Nothing, l) = l
@@ -47,7 +47,7 @@ groupJusts maybes = prepend $ foldr go (Nothing, []) maybes
     go (Just x) (Nothing, ls) = (Just $ x :| [], ls)
     go (Just x) (Just l , ls) = (Just $ x <| l , ls)
 
-groupEithers :: [Either a b] -> ([b], [(NonEmpty a, NonEmpty b)], [a])
+groupEithers :: Foldable f => f (Either a b) -> ([b], [(NonEmpty a, NonEmpty b)], [a])
 groupEithers = foldr go ([], [], [])
     where
     go (Left x) ([]  , []         , as) = ([], []                     , x : as)