diff --git a/lower/nic.go b/lower/nic.go
index 8e0935d..fd6fd76 100644
--- a/lower/nic.go
+++ b/lower/nic.go
@@ -92,6 +92,8 @@ func (nc *NIC) Start(m *link.Me) {
 			} else {
 				off = copy(buf2, rem)
 			}
+		} else {
+			off = 0
 		}
 	}
 }