Setting column width in VBA - easy, right?

[JoeMarfice]

I feel really stupid. I can't set the column width.

The following code /should/ shrink the page widths by a factor of two, roughly. Instead, it stops with an error on the col.Width line:
Object required.

Sub ShrinkOnce()

Dim sht As Worksheet
Dim col As Range

For Each sht In ActiveWorkbook.Worksheets
    For Each col In sht.Columns
        col.Width = 48# ' = col.Width / 2
    Next col
Next sht

End Sub

What INCREDIBLY OBVIOUS thing am I missing?