1 files changed, 6 insertions, 1 deletions

diff --git a/daemon/device.c b/daemon/device.c
index acedbdf..684e009 100644
--- a/daemon/device.c
+++ b/daemon/device.c
@@ -322,7 +322,12 @@ int device_start_connect(int device_id, uint16_t dport, struct mux_client *clien
 
 static void update_connection(struct mux_connection *conn)
 {
-        conn->sendable = conn->rx_win - (conn->tx_seq - conn->rx_ack);
+        uint32_t sent = conn->tx_seq - conn->rx_ack;
+
+        if(conn->rx_win > sent)
+                conn->sendable = conn->rx_win - sent;
+        else
+                conn->sendable = 0;
 
         if(conn->sendable > conn->ob_capacity)
                 conn->sendable = conn->ob_capacity;