Switched stem now slight gap from top washer?

[AmiableChimp]

I borrowed a 100mm stem from a mate at work as my Scott has a 110mm as standard - wanted to see if I liked the slightly shortened reach.

After fitting it, there is a slight gap at the top when I put the top fastener back on - i.e. the new stem doesn't sit flush with the silver part it clamps onto.

Do I need to add a shim of some description or do I need to go for a different stem type?

New stem fitted:




Old stem:

[AmiableChimp]

Thanks guys.

Bought a set of carbon spacers from Halfords on the way home and after fitting a 5mm one, everything is nice and tight again.

Cheers.