diff --git a/lib/hs/src/Thrift.hs b/lib/hs/src/Thrift.hs
index 58a304b..6580209 100644
--- a/lib/hs/src/Thrift.hs
+++ b/lib/hs/src/Thrift.hs
@@ -90,13 +90,13 @@
   deriving ( Show, Typeable )
 instance Exception AppExn
 
-writeAppExn :: (Protocol p, Transport t) => p t -> AppExn -> IO ()
+writeAppExn :: Protocol p => p -> AppExn -> IO ()
 writeAppExn pt ae = writeVal pt $ TStruct $ Map.fromList
                     [ (1, ("message", TString $ encodeUtf8 $ pack $ ae_message ae))
                     , (2, ("type", TI32 $ fromIntegral $ fromEnum (ae_type ae)))
                     ]
 
-readAppExn :: (Protocol p, Transport t) => p t -> IO AppExn
+readAppExn :: Protocol p => p -> IO AppExn
 readAppExn pt = do
     let typemap = Map.fromList [(1,("message",T_STRING)),(2,("type",T_I32))]
     TStruct fields <- readVal pt $ T_STRUCT typemap