--- happstack-server-7.4.2-orig/src/Happstack/Server/Internal/Monads.hs	2015-03-24 03:34:11.000000000 +1100
+++ happstack-server-7.4.2/src/Happstack/Server/Internal/Monads.hs	2015-04-04 15:20:58.273008986 +1100
@@ -173,7 +173,7 @@
 instance MonadTrans (ServerPartT) where
     lift m = withRequest (\_ -> lift m)
 
-instance (Monad m) => Monoid (ServerPartT m a) where
+instance (Monad m, MonadPlus m) => Monoid (ServerPartT m a) where
     mempty  = mzero
     mappend = mplus
 
@@ -486,7 +486,7 @@
 instance MonadTrans WebT where
     lift = WebT . lift . lift . lift
 
-instance (Monad m) => MonadPlus (WebT m) where
+instance (Monad m, MonadPlus m) => MonadPlus (WebT m) where
     -- | Aborts a computation.
     --
     -- This is primarily useful because 'msum' will take an array of
@@ -505,7 +505,7 @@
           lft (Left  r, _) = Left r
           lft (Right a, f) = Right (a, f)
 
-instance (Monad m) => Monoid (WebT m a) where
+instance (Monad m, MonadPlus m) => Monoid (WebT m a) where
     mempty = mzero
     mappend = mplus
 
@@ -561,7 +561,7 @@
               liftWebT (Just (Right x,f)) = pass (return x)>>= (\a -> return $ Just (Right a,f))
 
 -- | Deprecated: use 'msum'.
-multi :: Monad m => [ServerPartT m a] -> ServerPartT m a
+multi :: (Monad m, MonadPlus m) => [ServerPartT m a] -> ServerPartT m a
 multi = msum
 {-# DEPRECATED multi "Use msum instead" #-}
 
--- happstack-server-7.4.2-orig/src/Happstack/Server/RqData.hs	2015-03-24 03:34:11.000000000 +1100
+++ happstack-server-7.4.2/src/Happstack/Server/RqData.hs	2015-04-04 15:25:15.454830906 +1100
@@ -92,7 +92,7 @@
 newtype ReaderError r e a = ReaderError { unReaderError :: ReaderT r (Either e) a }
     deriving (Functor, Monad, MonadPlus)
 
-instance (Error e) => MonadReader r (ReaderError r e) where
+instance (Error e, Monoid e) => MonadReader r (ReaderError r e) where
     ask = ReaderError ask
     local f m = ReaderError $ local f (unReaderError m)
 
@@ -157,7 +157,7 @@
     rqDataError e = mapRqData ((Left e) `apEither`) (return ())
 
 -- instance (MonadPlus m, MonadIO m, ServerMonad m) => (HasRqData m) where
-instance (MonadIO m) => HasRqData (ServerPartT m) where
+instance (MonadIO m, MonadPlus m) => HasRqData (ServerPartT m) where
     askRqEnv =
         do rq  <- askRq
            mbi <- liftIO $ if ((rqMethod rq == POST) || (rqMethod rq == PUT)) && (isDecodable (ctype rq))