Error in TypeOf Expression in VB->C#

[Aleksander]

The following code produces the wrong C# code (if you convert back and forth you get a different meaning result):

If Not TypeOf tmp Is String Then
    ' yadayada
End If

The C# produced is 

if (!tmp is string) {
    // yadayada
}

Which probably doesn't even compile because you can't use ! on anything that could potentially be a string (might be mistaken about that though).