c-mode-base-map symbol is void

[nivpgir]

when using cpp-rtags-layer init is failing when loading keybindings.el cause of the following line:

(define-key c-mode-base-map (kbd "<C-tab>") 'company-complete)

I've managed to fix it for the moment by adding (require 'cc-mode) before the above line.
Somehow it feels like that's not the best solution for the problem, however, I am not very experienced with spacemacs layers, and don't know what is the appropriate place to to put such a fix.

I hope you'll know better than me.