What's up with this guy?

There is this guy at my work who seems to be sort of stalking me. I have known him since I started working there two years ago, but have never really talked to him much. He is from another dept and we rarely ever see each other, but we have been hosting Christmas parties for the past few weeks and I have to sort of work with him. He has been behaving out of character since we started working together. First he just kept coming by my office for stupid things and when I just ignored that, he started following me? For instance, today when I was walking around to make sure everything was perfect for the Christmas party, wherever I looked he was there. When I was talking to one of the bartenders, I felt someone behind me, and when I turned around he was standing there. Then when I was at the banquet office, he came there too. I left while he was talking with the banquet manager, and while I was on my way, I heard footsteps and when I looked behind, it was him! I would just keep on ignoring his behavior, except being followed is kind of disconcerting. I am not interested in any relationship and I don't want anyone at work to know about this. I also don't want to make it awkward working with him in the future. What should I do to get him to stop stalking me?