How to override evil-mode normal state binding

I am trying to override binding for 'q' for a minor mode. What is the right way to do it ? Using evil-define-key doesn't seem to work. For example i tried (evil-define-key 'normal magit-blame-mode "q" 'magit-blame-quit) and that doesn't seem to work. Even adding a new binding like (evil-define-key 'normal magit-blame-mode "Q" 'magit-blame-quit) is not working. I am using evil-mode from melpa -aneesh