Bug: doesn't actually make the image circular

[AndroidDeveloperLB]

I use this:

<FrameLayout
    xmlns:android="http://schemas.android.com/apk/res/android" xmlns:app="http://schemas.android.com/apk/res-auto"
    xmlns:tools="http://schemas.android.com/tools" android:layout_width="match_parent"
    android:layout_height="match_parent" tools:context=".MainActivity">

    <com.mklimek.circleinitialsview.CircleInitialsView
        android:layout_width="48dp" android:layout_height="48dp" android:layout_gravity="center"
        app:circleInitialsView_avatar="@drawable/pascal_avatar"/>
</FrameLayout>

Got the image here:

https://www.disneyexperience.com/downloads/avatars/pascal_avatar.jpg

And yet this is what I see: