Drawables in buttons don't have same color than the button's text

Hi there!

First of all, what a nice library!

Well, the issue is shown in the next picture (do not take into account the plus symbol):

As you can see I'm using text in some buttons and vector drawables in others, and they are not with the same color.
I've been trying lots of things (in the picture the plus symbol has android:fillColor="?backgroundColor") but I can get the things to have the same color.

Is there any button_text_color value which I could use in the fillColor of the drawables?

Well, thanks for your help, I hope I made myself understood.