Help modifying code

Could someone please help with the following code. My Zip codes are numeric.. and there is a note in the code stating the following:

caution if numeric zip codes, use CStr(c) instead

I have no idea where to go from here. Any help would be appreciated.

Thanks

Private Sub UserForm_Initialize() 
    Dim Coll As New Collection, c As  Range 
    Me.ComboBox1.Clear 
    On  Error Resume Next 
     ' duplicates elimination
    Var = [A1] 
    For Each c In Range([A2], [A65000].End(xlUp)) 
         ' caution if numeric zip codes, use CStr(c) instead
        Coll.Add c.Value, c.Value 
    Next c 
    On Error Goto 0 
     ' populates the combobox
    For Each Item In Coll 
        Me.ComboBox1.AddItem Item 
    Next Item 
End Sub