How do I keep a guy in my office from staring at my chest area?

There is a guy in my office that talks to me, but does not look me in the face. Now, I realize that I am a 34DDD which is large but not extremely huge. When he talks to me he seems to be talking to my breasts without looking at my face. I don't feel that this guy is creeping or anything like this. I feel that he doesn't realize what he is doing, but it does make me feel a bit uncomfortable. How do I convey this to him?

How do I keep a guy in my office from staring at my chest area?
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