Problems with gagging

Somiya • In love with a backpacker and graduating high school in 2017!
So I love to give head to my boyfriend because it makes him feel really great and I love hearing all the little noises he makes but I really don't love when I gag while giving him head. It's not a pleasant feeling and I don't know if there is a way to keep from gagging (it doesn't happen often but still) while still being able to give him head. Any suggestions?