List of GUIDS as stored procedure parameter

[Memnoch1207]

I'm trying to pass a comma separated list of GUIDs to a stored procedure but keep getting the following error

Syntax error converting from a character string to uniqueidentifier.

My stored procedure looks like this

CREATE PROCEDURE stp_GetProductNames
   @ManuID varchar(5000)
AS
SELECT DISTINCT A.ProductName
FROM Products As A
INNER JOIN Manfacuturers As B On (A.ManufacturerID = B.ManufacturerID)
WHERE A.ManufacturerID IN (@ManuID) 
ORDER BY A.ProductName

The list of GUIDS is the @ManuID parameter.
The GUIDS just look like this ('xxxxxxxx-xxxx-xxxx-xxxx-xxxxxxxxxxxx', 'xxxxxxxx-xxxx-xxxx-xxxx-xxxxxxxxxxxx')

Anyone know how to get around this error?