diff --git a/sys/net/sixlowpan/sixlownd.c b/sys/net/sixlowpan/sixlownd.c
index 7480554b22bd300d55be03eaa017ecc00ea32af3..652e8c2018dbc8daa4659a2620133269ccffb836 100644
--- a/sys/net/sixlowpan/sixlownd.c
+++ b/sys/net/sixlowpan/sixlownd.c
@@ -182,7 +182,7 @@ void init_rtr_sol(uint8_t sllao)
     ipv6_get_saddr(&(ipv6_buf->srcaddr), &(ipv6_buf->destaddr));
 
     opt_hdr_len = RTR_SOL_LEN;
-    ipv6_buf->length = ICMPV6_HDR_LEN + RTR_SOL_LEN + OPT_STLLAO_MAX_LEN;
+    ipv6_buf->length = HTONS(ICMPV6_HDR_LEN + RTR_SOL_LEN + OPT_STLLAO_MAX_LEN);
 
     if (sllao == OPT_SLLAO) {
         opt_stllao_buf = get_opt_stllao_buf(ipv6_ext_hdr_len, opt_hdr_len);
@@ -445,7 +445,7 @@ void init_rtr_adv(ipv6_addr_t *addr, uint8_t sllao, uint8_t mtu, uint8_t pi,
         }
     }
 
-    ipv6_buf->length = packet_length - IPV6_HDR_LEN;
+    ipv6_buf->length = HTONS(packet_length - IPV6_HDR_LEN);
 
     /* calculate checksum */
     icmp_buf->checksum = 0;
@@ -698,7 +698,7 @@ void init_nbr_sol(ipv6_addr_t *src, ipv6_addr_t *dest, ipv6_addr_t *targ,
         packet_length += OPT_ARO_HDR_LEN;
     }
 
-    ipv6_buf->length = packet_length - IPV6_HDR_LEN;
+    ipv6_buf->length = HTONS(packet_length - IPV6_HDR_LEN);
 
     icmp_buf->checksum = 0;
     icmp_buf->checksum = ~icmpv6_csum(PROTO_NUM_ICMPV6);
@@ -941,7 +941,7 @@ void init_nbr_adv(ipv6_addr_t *src, ipv6_addr_t *dst, ipv6_addr_t *tgt,
         packet_length += OPT_ARO_HDR_LEN;
     }
 
-    ipv6_buf->length = packet_length - IPV6_HDR_LEN;
+    ipv6_buf->length = HTONS(packet_length - IPV6_HDR_LEN);
 
     icmp_buf->checksum = 0;
     icmp_buf->checksum = ~icmpv6_csum(PROTO_NUM_ICMPV6);
@@ -1069,7 +1069,7 @@ uint16_t icmpv6_csum(uint8_t proto)
 {
     ipv6_buf = get_ipv6_buf();
     uint16_t sum;
-    uint16_t len = ipv6_buf->length;
+    uint16_t len = NTOHS(ipv6_buf->length);
     sum = len + proto;
 
     sum = csum(sum, (uint8_t *)&ipv6_buf->srcaddr, 2 * sizeof(ipv6_addr_t));
@@ -1109,7 +1109,7 @@ void init_para_prob(ipv6_addr_t *src, ipv6_addr_t *dest, uint8_t code, uint32_t
 
     packet_length += min(MTU - packet_length, packet_len);
 
-    ipv6_buf->length = packet_length - IPV6_HDR_LEN;
+    ipv6_buf->length = HTONS(packet_length - IPV6_HDR_LEN);
 
     icmp_buf->checksum = 0;
     icmp_buf->checksum = ~icmpv6_csum(PROTO_NUM_ICMPV6);