Pet Chat - Help; Puppy Annoys Older Dog!!!

I need help. Have a six month old puppy and a sixteen year old dog. They at times get on great, but the puppy contastly licks the older dogs face. As my puppy is a Shitzu, and my older dog a collie it means he has to jump at him to do this. My Collie growls at him when he does this, but im worried one day he might just snap. Most of the time they are really good together but this is really worrying. Can anyone help???