Grid auto column width text wrapping fail.

FailDemo.xaml

<Window x:Class="TestGridTextWrapping.MainWindow"
        xmlns="http://schemas.microsoft.com/winfx/2006/xaml/presentation"
        xmlns:x="http://schemas.microsoft.com/winfx/2006/xaml"
        Title="MainWindow" Height="350" Width="525">
    <Grid Width="525">
        <Grid.ColumnDefinitions>
            <ColumnDefinition Width="Auto" />
            <ColumnDefinition Width="*" />
        </Grid.ColumnDefinitions>
        
        <TextBlock TextWrapping="WrapWithOverflow">
            Blah blah blah blah some really long text that will need to wrap, but stupidly will not. I can't quite understand why the grid is letting the TextBlock measure with infinite width.
        </TextBlock>
    </Grid>
</Window>