What is the best way to have a conversation with someone who stutters?

What is the best way to have a conversation with someone who stutters? I met someone at work and asked what his name was, and quickly realized he had a major stutter. While I was waiting for him to say his name, I maintained eye contact, and kept a smile on my face. I stood there listening for about a minute, and then my boss pulled me away to help her with something, and I just said "sorry, I have to go! See you around!" So I didn't get to actually have a conversation with him. But in the event I see him again and try again, what's the best way to help him feel comfortable talking to me? I don't want him to think I'm being impatient or that he is annoying me. I know he can't help it.