diff --git a/src/add-ons/kernel/network/protocols/tcp/TCPEndpoint.cpp b/src/add-ons/kernel/network/protocols/tcp/TCPEndpoint.cpp
index 8a4a13ad19..67a9bb025a 100644
--- a/src/add-ons/kernel/network/protocols/tcp/TCPEndpoint.cpp
+++ b/src/add-ons/kernel/network/protocols/tcp/TCPEndpoint.cpp
@@ -1557,8 +1557,8 @@ TCPEndpoint::_WaitForEstablished(RecursiveLocker &locker, bigtime_t timeout)
 void
 TCPEndpoint::_AddData(tcp_segment_header &segment, net_buffer *buffer)
 {
-	fReceiveNext += buffer->size;
 	fReceiveQueue.Add(buffer, segment.sequence);
+	fReceiveNext = fReceiveQueue.LastSequence();
 
 	TRACE("  _AddData(): adding data, receive next = %lu. Now have %lu bytes.",
 		(uint32)fReceiveNext, fReceiveQueue.Available());