I'm making a general purpose N-ary tree and im coming up with "unexpected '=' on line 17" as an error. I have spent a fair while trying to work out why this isn't accepting the case that an Empty gtree returns false for any member search. i realise this is probably a very trivial error but any help would be appreciated:

module GTrees where

data Gtree = Empty |
             Leaf String |
             Node String [Gtree]
             deriving (Show)

--Tests if a given string is a member of the tree

gtreeMember :: (Ord a) => a -> Gtree a -> Bool
gtreeMember y Empty = False -- line 17
gtreeMember y (Leaf x) = (x==y)
gtreeMember y (Node x tree)
      |x==y = True
      |otherwise gtreeMember tree

This is the code up to the point of the error with the error line highlighted