special characters in layout xml of Android project

I again have a problem with special characters. In this case it is in a res\layout\mylayout.xml When using characters like 'ó' and 'í' my project doesn't compile.

<?xml version="1.0" encoding="utf-8"?>
<LinearLayout

    <RadioGroup
        android:id="@+id/radiosearchoptions"
        android:layout_width="wrap_content"
        android:layout_height="wrap_content" >

        <RadioButton
            android:id="@+id/searchtitleonly"
            android:layout_width="wrap_content"
            android:layout_height="wrap_content"
            android:text="buscar sólo en el título"

any hints ? thanks.