diff --git a/sys/net/gnrc/network_layer/ndp/router/gnrc_ndp_router.c b/sys/net/gnrc/network_layer/ndp/router/gnrc_ndp_router.c
index ab01e8b8ae..ce23cc7a7c 100644
--- a/sys/net/gnrc/network_layer/ndp/router/gnrc_ndp_router.c
+++ b/sys/net/gnrc/network_layer/ndp/router/gnrc_ndp_router.c
@@ -90,6 +90,7 @@ static void _send_rtr_adv(gnrc_ipv6_netif_t *iface, ipv6_addr_t *dst)
 
     mutex_lock(&iface->mutex);
     fin = (iface->adv_ltime == 0);
+    assert((iface->min_adv_int != 0) && (iface->max_adv_int != 0));
     interval = genrand_uint32_range(iface->min_adv_int, iface->max_adv_int);
     if (!fin && !((iface->flags | GNRC_IPV6_NETIF_FLAGS_ROUTER) &&
                   (iface->flags | GNRC_IPV6_NETIF_FLAGS_RTR_ADV))) {