diff --git a/app/Gyehoek/Sexp.hs b/app/Gyehoek/Sexp.hs
index c5ea7a2..c6f62d4 100644
--- a/app/Gyehoek/Sexp.hs
+++ b/app/Gyehoek/Sexp.hs
@@ -37,9 +37,9 @@ let_ name rhs e = list (el (sym "let") >>> el bindings >>> el e)
 data DotList a = MkDotList (NonEmpty a) a
   deriving (Show, Generic)
 
-dotlist :: Grammar Position _ _ -> _
+dotlist :: (forall t. Grammar Position (Sexp :- t) (a :- t)) -> _
 dotlist x = list $ rest $ coproduct
-  [ x >>> iso _ _
+  [ x >>> _
   ]
 
 lambda