How can I place Button or TextView at the absolute bottom in RelativLayout?

There seems to be some hidden padding in the RelativLayout, I'm I right?

I've got this TextView:

    <TextView
    android:layout_width="match_parent"
    android:layout_height="wrap_content"
    android:layout_alignParentBottom="true"
    android:background="@color/green"
    android:text="LOG IN"/>

in a RelativeLayout.

What I cant understand is why

    android:layout_alignParentBottom="true"

doesn't place the TextView all the way down. ref image:

Is there any way to remove this padding?