diff --git a/sys/netinet/sctp_uio.h b/sys/netinet/sctp_uio.h
index f19e3b9e0ff6..54d7457f90af 100644
--- a/sys/netinet/sctp_uio.h
+++ b/sys/netinet/sctp_uio.h
@@ -660,6 +660,7 @@ struct sctp_authkeyid {
 /* SCTP_PEER_AUTH_CHUNKS / SCTP_LOCAL_AUTH_CHUNKS */
 struct sctp_authchunks {
 	sctp_assoc_t gauth_assoc_id;
+	uint32_t gauth_number_of_chunks;
 	uint8_t gauth_chunks[];
 };
 
diff --git a/sys/netinet/sctp_usrreq.c b/sys/netinet/sctp_usrreq.c
index 83585d93220d..e5d793b840d2 100644
--- a/sys/netinet/sctp_usrreq.c
+++ b/sys/netinet/sctp_usrreq.c
@@ -2879,6 +2879,7 @@ sctp_getopt(struct socket *so, int optname, void *optval, size_t *optsize,
 				} else {
 					/* copy in the chunks */
 					(void)sctp_serialize_auth_chunks(chklist, sac->gauth_chunks);
+					sac->gauth_number_of_chunks = (uint32_t) size;
 					*optsize = sizeof(struct sctp_authchunks) + size;
 				}
 				SCTP_TCB_UNLOCK(stcb);
@@ -2897,6 +2898,7 @@ sctp_getopt(struct socket *so, int optname, void *optval, size_t *optsize,
 					} else {
 						/* copy in the chunks */
 						(void)sctp_serialize_auth_chunks(chklist, sac->gauth_chunks);
+						sac->gauth_number_of_chunks = (uint32_t) size;
 						*optsize = sizeof(struct sctp_authchunks) + size;
 					}
 					SCTP_INP_RUNLOCK(inp);
@@ -2927,6 +2929,7 @@ sctp_getopt(struct socket *so, int optname, void *optval, size_t *optsize,
 				} else {
 					/* copy in the chunks */
 					(void)sctp_serialize_auth_chunks(chklist, sac->gauth_chunks);
+					sac->gauth_number_of_chunks = (uint32_t) size;
 					*optsize = sizeof(struct sctp_authchunks) + size;
 				}
 				SCTP_TCB_UNLOCK(stcb);