diff --git a/net/rxrpc/ar-internal.h b/net/rxrpc/ar-internal.h
index 1ad0ec5afb50ce5817b3e79757240762b7034573..6c93a2fa96283fcd16fcefa2da7239263eb80e46 100644
--- a/net/rxrpc/ar-internal.h
+++ b/net/rxrpc/ar-internal.h
@@ -690,6 +690,7 @@ struct rxrpc_call {
 	rxrpc_seq_t		acks_lowest_nak; /* Lowest NACK in the buffer (or ==tx_hard_ack) */
 	rxrpc_seq_t		acks_lost_top;	/* tx_top at the time lost-ack ping sent */
 	rxrpc_serial_t		acks_lost_ping;	/* Serial number of probe ACK */
+	rxrpc_serial_t		acks_highest_serial; /* Highest serial number ACK'd */
 };
 
 /*
diff --git a/net/rxrpc/input.c b/net/rxrpc/input.c
index 721d847ba92bb26ad9d5380e3b739457a4234d67..4ba678f0c384d147d7b5f378bb776dd9bc3cb0d8 100644
--- a/net/rxrpc/input.c
+++ b/net/rxrpc/input.c
@@ -967,6 +967,10 @@ static void rxrpc_input_ack(struct rxrpc_call *call, struct sk_buff *skb)
 	call->acks_first_seq = first_soft_ack;
 	call->acks_prev_seq = prev_pkt;
 
+	if (buf.ack.reason != RXRPC_ACK_PING &&
+	    after(acked_serial, call->acks_highest_serial))
+		call->acks_highest_serial = acked_serial;
+
 	/* Parse rwind and mtu sizes if provided. */
 	if (buf.info.rxMTU)
 		rxrpc_input_ackinfo(call, skb, &buf.info);