VBA Fix Function Discrepancy?

Question

Why do the following two calls to the Fix function produce different results?

Private Sub Test_Fix()
    Dim d As Double

    d = -17.555

    Debug.Print "Fix(" & d & " * 1000) = " & Fix(d * 1000)

    d = d * 1000

    Debug.Print "Fix(" & d & ") = " & Fix(d)

    ' Output: 
    '     Fix(-17.555 * 1000) = -17554
    '     Fix(-17555) = -17555
End Sub

The second of the two calls give the result I would expect.

I assume the difference has something to do with inexact representation of some numbers as type Double, whereby the first call would actually compute something like Fix(-17.554999999). However, it still seems the two should produce consistent results since the d is of type Double.

The documentation mentions that the parameter can be

A number of type Double or any valid numeric expression.

Therefore, I would have assumed that both function calls above would be valid and produce identical results.