From e51b0c1e2b1e36962530904ba83eeb5b8a656e4c Mon Sep 17 00:00:00 2001
From: Martine Lenders <m.lenders@fu-berlin.de>
Date: Tue, 14 Nov 2017 22:46:24 +0100
Subject: [PATCH] gnrc_netif2: adapt setting of maximum packet size for slipdev

---
 sys/net/gnrc/netif2/gnrc_netif2.c | 11 ++++++++---
 1 file changed, 8 insertions(+), 3 deletions(-)

diff --git a/sys/net/gnrc/netif2/gnrc_netif2.c b/sys/net/gnrc/netif2/gnrc_netif2.c
index 18ea7ec008b5c..4fe016152a3fe 100644
--- a/sys/net/gnrc/netif2/gnrc_netif2.c
+++ b/sys/net/gnrc/netif2/gnrc_netif2.c
@@ -1100,10 +1100,15 @@ static void _init_from_device(gnrc_netif2_t *netif)
             break;
 #endif
         default:
-            res = dev->driver->get(dev, NETOPT_MAX_PACKET_SIZE, &tmp, sizeof(tmp));
-            assert(res == sizeof(tmp));
 #ifdef MODULE_GNRC_IPV6
-            netif->ipv6.mtu = tmp;
+            res = dev->driver->get(dev, NETOPT_MAX_PACKET_SIZE, &tmp, sizeof(tmp));
+            if (res < 0) {
+                /* assume maximum possible transition unit */
+                netif->ipv6.mtu = UINT16_MAX;
+            }
+            else {
+                netif->ipv6.mtu = tmp;
+            }
 #endif
     }
     _update_l2addr_from_dev(netif);