Android : Android EditText, minus converted to a dot event though inputType="number|numberSigned|numberDecimal"

I have a user who owns an LG VS890 4G with Android 4.4.2. Apparently each time when he tries to insert a minus in my lat/long coordinate input EditText, his minus gets converted into a dot.

        <EditText
        android:id="@+id/long_degrees_et_id"
        android:layout_width="0dp"
        android:layout_height="wrap_content"
        android:layout_weight="1"
        android:ems="10"
        android:inputType="number|numberSigned|numberDecimal" >

The thing is that he is experiencing this only on the soft keyboard. On the hard keyboard it works as expected.

Here is a screenshot with his phone while trying to input the coordinates:

He is the only one who reported this problem and I couldn't reproduce it. I would really like to keep the input type to number so that the keyboard opens automatically to numeric. Any ideas of how can I fix this?