diff --git a/Type/Spine/Base.hs b/Type/Spine/Base.hs
--- a/Type/Spine/Base.hs
+++ b/Type/Spine/Base.hs
@@ -52,8 +52,8 @@
 spineType_gen_ t ks = do
   let rhs = ConT ''Atom `AppT` t
       vars = [VarT $ mkName $ "t" ++ show i | i <- [0..]]
-  let snoc ty1 ty2 = ConT ''(:@) `AppT` ty1 `AppT` ty2
   return $ TySynInstD ''Spine [t] rhs :
     [ case take n vars of
-        vars -> TySynInstD ''Spine [foldl AppT t vars] $ foldl snoc t $ vars
+        vars -> TySynInstD ''Spine [foldl AppT t vars] $
+                  ConT ''(:@) `AppT` foldl AppT t (init vars) `AppT` last vars
       | n <- [1..length ks] ]
diff --git a/Type/Spine/TH.hs b/Type/Spine/TH.hs
--- a/Type/Spine/TH.hs
+++ b/Type/Spine/TH.hs
@@ -64,8 +64,8 @@
 -- | Returns the kinds of a type constructor's type parameters and range.
 tyConSignature :: Name -> Q ([Kind], Kind)
 tyConSignature n = do
-  let bad = fail "Type.Spine.TH.tyConSignature expects the name of a data/newtype/data family"
   i <- reify n
+  let bad = fail $ "Type.Spine.TH.tyConSignature expects the name of a data/newtype/data family; got " ++ show i
   case i of
     DataConI _ tys n _ -> return (getArgTypes tys, PromotedT n)
       where -- NB first, drop quantification over the data types' parameters
@@ -81,16 +81,16 @@
                     promote (AppT ty1 ty2) = AppT (promote ty1) (promote ty2)
                     promote (TupleT i) = PromotedTupleT i
                     promote ty =
-                      error $ "type-spine:tyConSignature: cannot promote" ++ show ty
+                      error $ "type-spine:tyConSignature: cannot promote " ++ show ty
             loop _ = [] -- this is the ctor's codomain, so ignore it
     TyConI dec -> case dec of
       DataD _ _ tvbs _ _ -> return (map tvb_kind tvbs, StarT)
       NewtypeD _ _ tvbs _ _ -> return (map tvb_kind tvbs, StarT)
-      FamilyD DataFam _ tvbs mk -> return (map tvb_kind tvbs, maybe StarT (peel tvbs) mk)
+      _ -> bad
+    FamilyI (FamilyD DataFam _ tvbs mk) _ -> return (map tvb_kind tvbs, maybe StarT (peel tvbs) mk)
         where peel [] k = k
               peel (_ : l) (AppT (AppT ArrowT _) r) = peel l r
               peel _ _ = error "Type.Spine.TH: bad FamilyD kind"
-      _ -> bad
     PrimTyConI _ i _ -> return (replicate i StarT, StarT)
     _ -> bad
 
diff --git a/type-spine.cabal b/type-spine.cabal
--- a/type-spine.cabal
+++ b/type-spine.cabal
@@ -1,5 +1,5 @@
 Name:           type-spine
-Version:        0.2
+Version:        0.2.20120924
 License:        BSD3
 License-File:   LICENSE
 Author:         Nicolas Frisby <nicolas.frisby@gmail.com>