Sub Remplit()
Dim tablo, ValA, A%, M%, DL%, L1%, L2%
A = 1: M = 13 ' pour simplifier la lecture
Application.ScreenUpdating = False
DL = Range("A65500").End(xlUp).Row
tablo = Range("A1:M" & DL)
For L1 = 1 To UBound(tablo)
If tablo(L1, M) = "" Then
ValA = tablo(L1, A)
For L2 = 1 To UBound(tablo)
If tablo(L2, A) = ValA And tablo(L2, M) <> "" Then
Cells(L1, "M") = Cells(L2, "M")
Exit For
End If
Next L2
End If
Next L1
End Sub