diff --git a/phpseclib/Net/SFTP.php b/phpseclib/Net/SFTP.php
index ca1f794a..5c71ee04 100644
--- a/phpseclib/Net/SFTP.php
+++ b/phpseclib/Net/SFTP.php
@@ -1793,12 +1793,12 @@ class Net_SFTP extends Net_SSH2
      * @param optional Integer $mode
      * @param optional Integer $start
      * @param optional Integer $local_start
-     * @param optional callable|null $callback
+     * @param optional callable|null $progressCallback
      * @return Boolean
      * @access public
      * @internal ASCII mode for SFTPv4/5/6 can be supported by adding a new function - Net_SFTP::setMode().
      */
-    function put($remote_file, $data, $mode = NET_SFTP_STRING, $start = -1, $local_start = -1, $callback = null)
+    function put($remote_file, $data, $mode = NET_SFTP_STRING, $start = -1, $local_start = -1, $progressCallback = null)
     {
         if (!($this->bitmap & NET_SSH2_MASK_LOGIN)) {
             return false;
@@ -1846,13 +1846,13 @@ class Net_SFTP extends Net_SSH2
         }
 
         // http://tools.ietf.org/html/draft-ietf-secsh-filexfer-13#section-8.2.3
-        $callback = false;
+        $dataCallback = false;
         switch (true) {
             case $mode & NET_SFTP_CALLBACK;
                 if (!is_callable($data)) {
                     user_error("\$data should be is_callable if you set NET_SFTP_CALLBACK flag");
                 }
-                $callback = $data;
+                $dataCallback = $data;
                 // do nothing
                 break;
             case is_resource($data):
@@ -1881,7 +1881,7 @@ class Net_SFTP extends Net_SSH2
             } else {
                 fseek($fp, $offset);
             }
-        } elseif ($callback) {
+        } elseif ($dataCallback) {
             $size = 0;
         } else {
             $size = strlen($data);
@@ -1894,9 +1894,9 @@ class Net_SFTP extends Net_SSH2
         // 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;
         $i = 0;
-        while ($callback || ($sent < $size)) {
-            if ($callback) {
-                $temp = call_user_func($callback, $sftp_packet_size);
+        while ($dataCallback || ($sent < $size)) {
+            if ($dataCallback) {
+                $temp = call_user_func($dataCallback, $sftp_packet_size);
                 if (is_null($temp)) {
                     break;
                 }
@@ -1912,8 +1912,8 @@ class Net_SFTP extends Net_SSH2
                 return false;
             }
             $sent+= strlen($temp);
-            if (is_callable($callback)) {
-                call_user_func($callback, $sent);
+            if (is_callable($progressCallback)) {
+                call_user_func($progressCallback, $sent);
             }
 
             $i++;