H列が同じのに色

Sub 同じのに色()
    Dim N As Long
    Dim buf1, buf2 As String
    N = 2 '初期値
        Do While Cells(N, 1).Value <> ""
            buf1 = Cells(N - 1, 8)
            buf2 = Cells(N, 8)
            If buf2 = buf1 Then
                Cells(N - 1, 8).Interior.ColorIndex = 36 '黄色
                Cells(N, 8).Interior.ColorIndex = 36 '黄色
            End If
            N = N + 1
        Loop
End Sub