diff --git a/net/ipv4/tcp_ipv4.c b/net/ipv4/tcp_ipv4.c
index 4a46da375043..aada52769057 100644
--- a/net/ipv4/tcp_ipv4.c
+++ b/net/ipv4/tcp_ipv4.c
@@ -971,6 +971,9 @@ static void tcp_v4_send_ack(const struct sock *sk,
 					  key->rcv_next);
 		arg.iov[0].iov_len += tcp_ao_len_aligned(key->ao_key);
 		rep.th.doff = arg.iov[0].iov_len / 4;
+		memset((u8 *)&rep.opt[offset] + tcp_ao_maclen(key->ao_key),
+		       TCPOPT_NOP, tcp_ao_len_aligned(key->ao_key) -
+				    tcp_ao_len(key->ao_key));
 
 		tcp_ao_hash_hdr(AF_INET, (char *)&rep.opt[offset],
 				key->ao_key, key->traffic_key,
diff --git a/net/ipv6/tcp_ipv6.c b/net/ipv6/tcp_ipv6.c
index 522ba45ce9b7..9e9155b1b3aa 100644
--- a/net/ipv6/tcp_ipv6.c
+++ b/net/ipv6/tcp_ipv6.c
@@ -923,6 +923,8 @@ static void tcp_v6_send_response(const struct sock *sk, struct sk_buff *skb, u32
 				(tcp_ao_len(key->ao_key) << 16) |
 				(key->ao_key->sndid << 8) |
 				(key->rcv_next));
+		memset((u8 *)topt + tcp_ao_maclen(key->ao_key), TCPOPT_NOP,
+		       tcp_ao_len_aligned(key->ao_key) - tcp_ao_len(key->ao_key));
 
 		tcp_ao_hash_hdr(AF_INET6, (char *)topt, key->ao_key,
 				key->traffic_key,