diff --git a/gtests/net/packetdrill/tests/bsd/tcp/fast_retransmit/fr-4pkt-sack-bsd.pkt b/gtests/net/packetdrill/tests/bsd/tcp/fast_retransmit/fr-4pkt-sack-bsd.pkt
index 1980739f453374ae1deb9926f19d7ab5ea043429..9539df2a3e26c54ca615228fdbc020268b7c80fe 100644
--- a/gtests/net/packetdrill/tests/bsd/tcp/fast_retransmit/fr-4pkt-sack-bsd.pkt
+++ b/gtests/net/packetdrill/tests/bsd/tcp/fast_retransmit/fr-4pkt-sack-bsd.pkt
@@ -35,4 +35,4 @@
 +0  > . 1001:2001(1000) ack 1
 
 // Receiver ACKs all data.
-+.1 < . 1:1(0) ack 6001 win 257
++.1 < . 1:1(0) ack 5001 win 257