Can I change the swatch icon background color?

My swatches are white patterns on transparent backgrounds.
But because the swatch icons have white backgrounds, I will not be able to distinguish my swatches by looking at their icon.
I don't want a black background for the swatch itself, it needs to be transparent, and it is.
I just want to change the swatch icon background color to black so I can distinguish my swatches by looking at their icons.
