--- a/pppd/sys-linux.c
+++ b/pppd/sys-linux.c
@@ -1717,6 +1717,7 @@ int cifdefaultroute (int unit, u_int32_t
 	SIN_ADDR(rt.rt_genmask) = 0L;
     }
 
+    rt.rt_dev = ifname;
     rt.rt_flags = RTF_UP;
     if (ioctl(sock_fd, SIOCDELRT, &rt) < 0 && errno != ESRCH) {
 	if (still_ppp()) {
