diff --git a/Biobase/Primary/Letter.hs b/Biobase/Primary/Letter.hs
index e76015a..6a2ef60 100644
--- a/Biobase/Primary/Letter.hs
+++ b/Biobase/Primary/Letter.hs
@@ -137,6 +137,11 @@ deriving instance (Read (Letter l n)) => Read    (LimitType (Letter l n))
 deriving instance (Show (Letter l n)) => Show    (LimitType (Letter l n))
 deriving instance Typeable (LimitType (Letter l n))
 deriving instance Data (Letter l n) => Data (LimitType (Letter l n))
+instance Binary    (LimitType (Letter l n))
+instance Serialize (LimitType (Letter l n))
+instance ToJSON    (Letter l n) => ToJSON    (LimitType (Letter l n))
+instance FromJSON  (Letter l n) => FromJSON  (LimitType (Letter l n))
+instance Hashable  (LimitType (Letter l n))
 
 instance IndexStream z => IndexStream (z:.Letter l n) where
   streamUp (ls:..LtLetter l) (hs:..LtLetter h) = flatten mk step $ streamUp ls hs