Resolved questions
"You can talk informally to me"

Hello, as I'm half korean I have quite many korean friends and I'm quite familiar with the politeness levels. Everytime we ask for each other's age or just find it out, then start out talking 반말 or in the other case 'formally'. I have a friend of mine (who's more than one year older) that keeps talking in the ㅂ니다 form and I'm starting feeling really awkward. I'd like to tell my friend "You can use informal language with me / please talk comfortably with me".

Is 편안하게 말해주세요 correct?

Thanks for help!!