If @Title IS NULL Not Working

I'm building a stored procedure to edit a row in my database but first I'm wanting to check for null values in the parameters and set them to their respective value in the row I'm attempting to edit.

Here's my code:

Code:

CREATE PROCEDURE dbo.spModifyProject
(
@ProjectID int,
@Title nvarchar(50),
@Description nvarchar(50),
@DueDate smalldatetime,
@ProjectLead nvarchar(50),
@Completed bit
)

AS

IF @Title IS Null Then
SET @Title = (SELECT Title FROM Projects WHERE [ID] = @ProjectID)
END IF



I get syntax errors in two places. The first is near Null and the second is near END. Any help you can give is appreciated.