pattern-matching with labelled types

If I have:

data MyType = MT { x :: Int, y :: Char }

How do I update the Int value of MyType leaving the Char value unaffected? I tryied something like:

MT {x = newValue}

but GHC gave me a warning about the Char value and it indeed caused strange effects. Of course, it is possible to do something like

update :: MyType -> Int -> MyType update mt newValue = MT {x = newValue, y = oldValue} where oldValue = y mt

but this really annoys me when MyType has too many fields. Suggestions? Thanks a lot, -- Andre