Changing the appearance of a custom android checkbox without the image scaling?

Question

I have a custom checkbox with these attributes:

android:id="@+id/map_toolbar_details"
android:layout_width="80px"
android:layout_height="106px"
android:scaleType="center"
macro:selectedResource="@drawable/map_toolbar_details_selected"
android:button="@drawable/map_toolbar_details"

When I load it up, the image gets stretched, even though it's set to scaleType center. If I set a background, I do not have this problem.