diff --git a/elm-bridge.cabal b/elm-bridge.cabal
--- a/elm-bridge.cabal
+++ b/elm-bridge.cabal
@@ -1,5 +1,5 @@
 name:                elm-bridge
-version:             0.8.3
+version:             0.8.4
 synopsis:            Derive Elm types and Json code from Haskell types, using aeson's options
 description:         Building the bridge from Haskell to Elm and back. Define types once,
                      and derive the aeson and elm functions at the same time, using any aeson
diff --git a/src/Elm/Derive.hs b/src/Elm/Derive.hs
--- a/src/Elm/Derive.hs
+++ b/src/Elm/Derive.hs
@@ -94,7 +94,7 @@
         TaggedObject tn cn    -> [|SumEncoding' (TaggedObject tn cn)|]
         UntaggedValue         -> [|SumEncoding' UntaggedValue|]
 
-runDerive :: Name -> [TyVarBndr ()] -> (Q Exp -> Q Exp) -> Q [Dec]
+runDerive :: Name -> [TyVarBndr a] -> (Q Exp -> Q Exp) -> Q [Dec]
 runDerive name vars mkBody =
     liftM (:[]) elmDefInst
     where
@@ -125,7 +125,7 @@
                 PlainTV tv _  -> tv
                 KindedTV tv _ _ -> tv
 
-deriveAlias :: Bool -> A.Options -> Name -> [TyVarBndr ()] -> [VarStrictType] -> Q [Dec]
+deriveAlias :: Bool -> A.Options -> Name -> [TyVarBndr a] -> [VarStrictType] -> Q [Dec]
 deriveAlias isNewtype opts name vars conFields =
         runDerive name vars $ \typeName ->
                 [|ETypeAlias (EAlias $typeName $fields omitNothing isNewtype unwrapUnary)|] -- default to no newtype
@@ -140,7 +140,7 @@
             fldName = A.fieldLabelModifier opts $ nameBase fname
             fldType = compileType ftype
 
-deriveSum :: A.Options -> Name -> [TyVarBndr ()] -> [Con] -> Q [Dec]
+deriveSum :: A.Options -> Name -> [TyVarBndr a] -> [Con] -> Q [Dec]
 deriveSum opts name vars constrs =
     runDerive name vars $ \typeName ->
         [|ETypeSum (ESum $typeName $sumOpts $sumEncOpts omitNothing allNullary)|]
@@ -164,7 +164,7 @@
                 in [|STC b n (Named $tyArgs)|]
             _ -> fail ("Can't derive this sum: " ++ show c)
 
-deriveSynonym :: A.Options -> Name -> [TyVarBndr ()] -> Type -> Q [Dec]
+deriveSynonym :: A.Options -> Name -> [TyVarBndr a] -> Type -> Q [Dec]
 deriveSynonym _ name vars otherT =
     runDerive name vars $ \typeName ->
         [|ETypePrimAlias (EPrimAlias $typeName $otherType)|]
diff --git a/src/Elm/TyRep.hs b/src/Elm/TyRep.hs
--- a/src/Elm/TyRep.hs
+++ b/src/Elm/TyRep.hs
@@ -3,6 +3,7 @@
 -}
 module Elm.TyRep where
 
+import qualified Data.Char        as Char
 import           Data.List
 import           Data.Proxy
 import           Data.Typeable    (TyCon, TypeRep, Typeable, splitTyConApp,
@@ -84,8 +85,8 @@
 
 isEmpty :: SumTypeFields -> Bool
 isEmpty (Anonymous []) = True
-isEmpty (Named []) = True
-isEmpty _ = False
+isEmpty (Named [])     = True
+isEmpty _              = False
 
 data SumTypeConstructor
     = STC
@@ -186,7 +187,9 @@
                 (con, args) = splitTyConApp rep
 
         isTuple :: String -> Bool
-        isTuple ('(':xs) = isTuple' $ reverse xs
+        isTuple "Unit" = True
+        isTuple ('T': 'u' : 'p': 'l' : 'e' : ds) = all Char.isDigit ds
+        isTuple ('(':xs) = isTuple' $ reverse xs -- base <= 4.17
           where
             isTuple' :: String -> Bool
             isTuple' (')':xs') = all (== ',') xs'