Multiple data selection from drop down list --> to single cell

Worksheet_change event is used.Pl see file.
K5 Validated cell, M5 is the destination cell.
If M5 is not having the value of K5, then pnly it will add. This avoids duplication.
code

Private Sub Worksheet_Change(ByVal Target As Range)
If Target.Address = "$K$5" Then

Application.EnableEvents = False
    If InStr(1, Range("M5"), Range("K5")) = 0 Then
    Range("M5") = Range("M5") & "," & Range("K5")
    End If

Application.EnableEvents = True
End If
End Sub