Toggle a Bit type ie not field

Here's the SP that toggles a Bit datatype. How would I make it comething
like
???
update pcpmanufacturers set def = not (def) where ManufID = @ManufID

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create Procedure pcp_manufToggle
@ManufID int

as

Set nocount on

declare @S as bit
select @s = def from pcpManufacturers where ManufID = @ManufID

if (@s = 1) begin
update pcpManufacturers set def=0 where manufID = @ManufID
end
else beginupdate pcpmanufacturers set def=1 where manufid = @manufID
end

TIA

Pete