diff --git a/Web/Routes/Quasi/Classes.hs b/Web/Routes/Quasi/Classes.hs
--- a/Web/Routes/Quasi/Classes.hs
+++ b/Web/Routes/Quasi/Classes.hs
@@ -14,13 +14,13 @@
     fromSinglePiece :: String -> Either String s
     toSinglePiece :: s -> String
 instance SinglePiece String where
-    fromSinglePiece = Right
+    fromSinglePiece s = if null s then Left "Empty string" else Right s
     toSinglePiece = id
 instance SinglePiece S.Text where
-    fromSinglePiece = Right . S.pack
+    fromSinglePiece s = if null s then Left "Empty string" else Right (S.pack s)
     toSinglePiece = S.unpack
 instance SinglePiece L.Text where
-    fromSinglePiece = Right . L.pack
+    fromSinglePiece s = if null s then Left "Empty string" else Right (L.pack s)
     toSinglePiece = L.unpack
 instance SinglePiece Integer where
     fromSinglePiece s = case reads s of
diff --git a/Web/Routes/Quasi/TH.hs b/Web/Routes/Quasi/TH.hs
--- a/Web/Routes/Quasi/TH.hs
+++ b/Web/Routes/Quasi/TH.hs
@@ -26,6 +26,7 @@
         , ssPieces :: [Piece]
         }
   | Simple [Piece] [String] -- ^ methods
+    deriving Show
 type THResource = (String, Pieces)
 
 createRoutes :: [THResource] -> Q [Con]
@@ -116,6 +117,7 @@
         return $ Clause [pat] (NormalB $ cons bod r') []
     go' (_, StaticPiece _) = Nothing
     go' (i, _) = Just $ VarP $ mkName $ "var" ++ show (i :: Int)
+    mkBod :: (Show t) => [(t, Piece)] -> Q Exp
     mkBod [] = lift ([] :: [String])
     mkBod ((_, StaticPiece x):xs) = do
         x' <- lift x
@@ -169,6 +171,7 @@
                -> Q [Clause]
 createDispatch modMaster toMaster = mapM go
   where
+    go :: (String, Pieces) -> Q Clause
     go (n, Simple ps methods) = do
         meth <- newName "method"
         xs <- mapM newName $ replicate (length $ filter notStatic ps) "x"
diff --git a/web-routes-quasi.cabal b/web-routes-quasi.cabal
--- a/web-routes-quasi.cabal
+++ b/web-routes-quasi.cabal
@@ -1,5 +1,5 @@
 name:            web-routes-quasi
-version:         0.6.3
+version:         0.6.3.1
 license:         BSD3
 license-file:    LICENSE
 author:          Michael Snoyman <michael@snoyman.com>