diff -r dd873f3119b2 src/internet/model/tcp-socket-base.cc
--- a/src/internet/model/tcp-socket-base.cc
+++ b/src/internet/model/tcp-socket-base.cc
@@ -2100,7 +2100,7 @@
 uint16_t
 TcpSocketBase::AdvertisedWindowSize ()
 {
-  uint32_t w = m_rxBuffer->MaxBufferSize () - m_rxBuffer->Size ();
+  uint32_t w = m_rxBuffer->MaxBufferSize ();
 
   w >>= m_sndScaleFactor;