diff --git a/net/tcp/tcp_recvwindow.c b/net/tcp/tcp_recvwindow.c
index 8de655dce9d..1b0d80ead49 100644
--- a/net/tcp/tcp_recvwindow.c
+++ b/net/tcp/tcp_recvwindow.c
@@ -52,6 +52,48 @@
 
 #include "tcp/tcp.h"
 
+/****************************************************************************
+ * Static Functions
+ ****************************************************************************/
+
+static int tcp_iob_navail(FAR struct net_driver_s *dev,
+                          FAR struct tcp_conn_s *conn)
+{
+  FAR struct tcp_conn_s *next = NULL;
+  int avail = iob_navail(true);
+  int count = 0;
+
+  while ((next = tcp_nextconn(next)) != NULL)
+    {
+      if (!IOB_QEMPTY(&next->readahead))
+        {
+          count++;
+        }
+    }
+
+  if (count == 0)
+    {
+      return avail;
+    }
+
+  if (avail > CONFIG_IOB_NBUFFERS / count)
+    {
+      avail = CONFIG_IOB_NBUFFERS / count;
+    }
+
+  count = iob_get_queue_count(&conn->readahead);
+  if (avail > count)
+    {
+      avail -= count;
+    }
+  else
+    {
+      avail = 0;
+    }
+
+  return avail;
+}
+
 /****************************************************************************
  * Public Functions
  ****************************************************************************/
@@ -112,7 +154,7 @@ uint16_t tcp_get_recvwindow(FAR struct net_driver_s *dev,
    * (ignoring competition with other IOB consumers).
    */
 
-  niob_avail    = iob_navail(true);
+  niob_avail    = tcp_iob_navail(dev, conn);
   nqentry_avail = iob_qentry_navail();
 
   /* Is there a a queue entry and IOBs available for read-ahead buffering? */