diff --git a/pscp.c b/pscp.c
index f6f6c206..9ea423fd 100644
--- a/pscp.c
+++ b/pscp.c
@@ -658,6 +658,10 @@ int sftp_senddata(char *buf, int len)
     back->send(backhandle, buf, len);
     return 1;
 }
+int sftp_sendbuffer(void)
+{
+    return back->sendbuffer(backhandle);
+}
 
 /* ----------------------------------------------------------------------
  * sftp-based replacement for the hacky `pscp -ls'.
diff --git a/psftp.c b/psftp.c
index 784c81b1..a718b794 100644
--- a/psftp.c
+++ b/psftp.c
@@ -2618,6 +2618,10 @@ int sftp_senddata(char *buf, int len)
     back->send(backhandle, buf, len);
     return 1;
 }
+int sftp_sendbuffer(void)
+{
+    return back->sendbuffer(backhandle);
+}
 
 /*
  *  Short description of parameters.
diff --git a/sftp.c b/sftp.c
index b4421f77..591b60ba 100644
--- a/sftp.c
+++ b/sftp.c
@@ -1349,7 +1349,7 @@ struct fxp_xfer *xfer_upload_init(struct fxp_handle *fh, uint64 offset)
 
 int xfer_upload_ready(struct fxp_xfer *xfer)
 {
-    if (xfer->req_totalsize < xfer->req_maxsize)
+    if (sftp_sendbuffer() == 0)
 	return 1;
     else
 	return 0;
diff --git a/sftp.h b/sftp.h
index c61340c1..309845b0 100644
--- a/sftp.h
+++ b/sftp.h
@@ -63,8 +63,12 @@
  * until len is available, or it returns failure.
  * 
  * Both functions return 1 on success, 0 on failure.
+ *
+ * sftp_sendbuffer returns the size of the backlog of data in the
+ * transmit queue.
  */
 int sftp_senddata(char *data, int len);
+int sftp_sendbuffer(void);
 int sftp_recvdata(char *data, int len);
 
 /*