Need advise please! Cushion from jumper

[BooRadders]

I have been stalling on making this cushion from a jumper as I fear it might not go well. Have bought a cheap jumper to test my pattern, but my question is, if it is made from a knitted jumper, am I in danger of it unravelling? Do I need to do anything special to the seams, or will a normal machine stitch work? Can't help thinking it will not last if I only use a straight line stitch!
Any hints gratefully received!

Felt it? If it is pure wool then a hot wash will do the trick. No danger of unravelling then. it will of course be smaller and felted then...which you may not want. And if it isnt pure wool it wont felt.

Otherwise I think it might well unravel and I would zigzag the edges with a fairly wide zigzag stitch as soon as I cut it.

I'd suggest stitching it before you cut it with a straight line of stitching (i.e. stitch the outer line of your jumper right through both thicknesses at least once for three sides and once on each thickness for the fourth side), then cut it out then zig zag the raw edges. Should do the trick!

Thanks for the replies....the felting would be a good solution, but I want to keep the wool look.....plus my test jumper isn't pure wool!
Will try the stitching solution.