How do you tell someone that you do not like them talking about you behind your back in a way that is not offensive to them?

Personally I would first make sure that they are talking behind my back and if this is true I would go talk to them in a non-agressive manner. Trying to here what they want to say and why they talked about me in the fist place. I would also stress the fact that them talking behind my back upset me and hurt me. Then I would ask them to not do it again and please in future to come talk to me fist before saying anything about me.