diff --git a/sys/include/net/gnrc/pktbuf.h b/sys/include/net/gnrc/pktbuf.h
index 91f9aa06e1a34d0220a8e923cca21b81818bcb8b..f9f29850b7b213851ff8a3d549e2537c53db9f9a 100644
--- a/sys/include/net/gnrc/pktbuf.h
+++ b/sys/include/net/gnrc/pktbuf.h
@@ -285,6 +285,11 @@ gnrc_pktsnip_t *gnrc_pktbuf_reverse_snips(gnrc_pktsnip_t *pkt);
  *
  *        The original snip is keeped as is except `users` decremented.
  *
+ * @deprecated  This function breaks the abstraction of `gnrc_pktbuf` and its
+ *              only user within the RIOT code base `gnrc_ipv6_ext` is going to
+ *              be reworked so it isn't needed anymore.
+ *              It will be removed after the 2019.04 release.
+ *
  * @param[in,out] pkt   The snip to duplicate.
  * @param[in]     type  The type of snip to stop duplication.
  *