What am I doing wrong? Command prompt *SOLVED*

Shade

So I need to do a mass file extension change. but I need it to go through the subfolders as well. I'm using command prompt and this is what I'm using but I keep getting a syntax error:

for /R %i in (*.cbr) do ren %i *.rar

any ideas?

EDIT: Turns out I forgot the " " around %i