diff --git a/sys/net/gnrc/network_layer/ipv6/gnrc_ipv6.c b/sys/net/gnrc/network_layer/ipv6/gnrc_ipv6.c
index 9e1bd1b159e4..f136f96e9a63 100644
--- a/sys/net/gnrc/network_layer/ipv6/gnrc_ipv6.c
+++ b/sys/net/gnrc/network_layer/ipv6/gnrc_ipv6.c
@@ -563,28 +563,33 @@ static void _send_multicast(gnrc_pktsnip_t *pkt, bool prep_hdr,
         gnrc_pktbuf_hold(pkt, ifnum - 1);
 
         while ((netif = gnrc_netif_iter(netif))) {
+            gnrc_pktsnip_t *send_pkt = pkt;
+            /* for !prep_hdr just use pkt as we don't duplicate IPv6 header as
+             * it is already filled and thus isn't filled with potentially
+             * interface-specific data */
             if (prep_hdr) {
                 DEBUG("ipv6: prepare IPv6 header for sending\n");
                 /* need to get second write access (duplication) to fill IPv6
-                 * header interface-local */
-                gnrc_pktsnip_t *tmp = gnrc_pktbuf_start_write(pkt);
+                 * header with interface-specific data */
+                send_pkt = gnrc_pktbuf_start_write(pkt);
 
-                if (tmp == NULL) {
+                if (send_pkt == NULL) {
                     DEBUG("ipv6: unable to get write access to IPv6 header, "
                           "for interface %" PRIkernel_pid "\n", netif->pid);
                     gnrc_pktbuf_release(pkt);
                     return;
                 }
-                if (_fill_ipv6_hdr(netif, tmp) < 0) {
+                if (_fill_ipv6_hdr(netif, send_pkt) < 0) {
                     /* error on filling up header */
-                    if (tmp != pkt) {
-                        gnrc_pktbuf_release(tmp);
+                    if (send_pkt != pkt) {
+                        gnrc_pktbuf_release(send_pkt);
                     }
                     gnrc_pktbuf_release(pkt);
                     return;
                 }
             }
-            _send_multicast_over_iface(pkt, prep_hdr, netif, netif_hdr_flags);
+            _send_multicast_over_iface(send_pkt, prep_hdr, netif,
+                                       netif_hdr_flags);
         }
     }
     else {