diff --git a/derive-trie.cabal b/derive-trie.cabal
--- a/derive-trie.cabal
+++ b/derive-trie.cabal
@@ -1,5 +1,5 @@
 Name:          derive-trie
-Version:       0.2
+Version:       0.2.1
 Stability:     Provisional
 Synopsis:      Automatic derivation of Trie implementations.
 Description:   Automatic derivation of Trie implementations from user
diff --git a/src/Data/Derive/Trie.hs b/src/Data/Derive/Trie.hs
--- a/src/Data/Derive/Trie.hs
+++ b/src/Data/Derive/Trie.hs
@@ -58,7 +58,6 @@
 import qualified Data.IntMap
 import Data.Array
 
-
 -- trie types for some primitive types like Int,Char, ..
 prim2trie :: [(Type,Type)]
 prim2trie = [(ConT ''Int,    ConT ''Data.IntMap.IntMap),
@@ -432,6 +431,7 @@
 -- replaces recursively every key type by the corresponding trie type, as
 -- specified in key2trie
 replaceKeyByTrie :: [(Type,Type)] -> Type -> Type
+replaceKeyByTrie key2trie ListT = replaceKeyByTrie key2trie $ ConT ''[]
 replaceKeyByTrie key2trie (AppT t1 t2) =
    AppT (replaceKeyByTrie key2trie t1) (replaceKeyByTrie key2trie t2)
 replaceKeyByTrie key2trie keyType =
@@ -603,7 +603,7 @@
     DataD _ _ _ cons _ -> return cons
     NewtypeD _ _ _ con _ -> return [con]
     TySynD name _ t    -> do
-       let (ConT newname) = getOutermostTypeOfType t
+       let ConT newname =  getOutermostTypeOfType t
        tdec <- doReify knownDecs newname
        getConstrsOfDataDec knownDecs tdec
     _                 -> error "Error:getConstrsOfDataDec: not implemented!"
@@ -620,6 +620,7 @@
 
 getOutermostTypeOfType :: Type -> Type
 getOutermostTypeOfType (AppT t1 t2) = getOutermostTypeOfType t1
+getOutermostTypeOfType ListT = ConT ''[]
 getOutermostTypeOfType t = t
 
 -- returns the constructor for the empty trie