diff --git a/phpseclib/Net/SFTP.php b/phpseclib/Net/SFTP.php
index 074b4f7f..5698319d 100644
--- a/phpseclib/Net/SFTP.php
+++ b/phpseclib/Net/SFTP.php
@@ -397,6 +397,9 @@ class SFTP extends SSH2
         if (!defined('NET_SFTP_QUEUE_SIZE')) {
             define('NET_SFTP_QUEUE_SIZE', 32);
         }
+        if (!defined('NET_SFTP_UPLOAD_QUEUE_SIZE')) {
+            define('NET_SFTP_UPLOAD_QUEUE_SIZE', 1024);
+        }
     }
 
     /**
@@ -2018,7 +2021,7 @@ class SFTP extends SSH2
         $sftp_packet_size = 4096; // PuTTY uses 4096
         // make the SFTP packet be exactly 4096 bytes by including the bytes in the NET_SFTP_WRITE packets "header"
         $sftp_packet_size-= strlen($handle) + 25;
-        $i = 0;
+        $i = $j = 0;
         while ($dataCallback || ($size === 0 || $sent < $size)) {
             if ($dataCallback) {
                 $temp = call_user_func($dataCallback, $sftp_packet_size);
@@ -2034,7 +2037,7 @@ class SFTP extends SSH2
 
             $subtemp = $offset + $sent;
             $packet = pack('Na*N3a*', strlen($handle), $handle, $subtemp / 4294967296, $subtemp, strlen($temp), $temp);
-            if (!$this->_send_sftp_packet(NET_SFTP_WRITE, $packet)) {
+            if (!$this->_send_sftp_packet(NET_SFTP_WRITE, $packet, $j)) {
                 if ($mode & self::SOURCE_LOCAL_FILE) {
                     fclose($fp);
                 }
@@ -2046,8 +2049,9 @@ class SFTP extends SSH2
             }
 
             $i++;
+            $j++;
 
-            if ($i == NET_SFTP_QUEUE_SIZE) {
+            if ($i == NET_SFTP_UPLOAD_QUEUE_SIZE) {
                 if (!$this->_read_put_responses($i)) {
                     $i = 0;
                     break;