diff --git a/lib/phpxmlrpc/Helper/Date.php b/lib/phpxmlrpc/Helper/Date.php
index bc60cc4869d..a9eb3012d3c 100644
--- a/lib/phpxmlrpc/Helper/Date.php
+++ b/lib/phpxmlrpc/Helper/Date.php
@@ -23,14 +23,9 @@ class Date
     public static function iso8601Encode($timet, $utc = 0)
     {
         if (!$utc) {
-            $t = strftime("%Y%m%dT%H:%M:%S", $timet);
+            $t = date('Ymd\TH:i:s', $timet);
         } else {
-            if (function_exists('gmstrftime')) {
-                // gmstrftime doesn't exist in some versions of PHP
-                $t = gmstrftime("%Y%m%dT%H:%M:%S", $timet);
-            } else {
-                $t = strftime("%Y%m%dT%H:%M:%S", $timet - date('Z'));
-            }
+            $t = gmdate('Ymd\TH:i:s', $timet);
         }
 
         return $t;
diff --git a/lib/phpxmlrpc/Helper/XMLParser.php b/lib/phpxmlrpc/Helper/XMLParser.php
index f6e79a9a0fa..d3595c3a981 100644
--- a/lib/phpxmlrpc/Helper/XMLParser.php
+++ b/lib/phpxmlrpc/Helper/XMLParser.php
@@ -315,7 +315,7 @@ class XMLParser
                         $this->_xh['ac'] = ''; // reset the accumulator
                         break;
                     }
-                // we do not support the <NIL/> extension, so
+                // if here, we do not support the <NIL/> extension, so
                 // drop through intentionally
                 default:
                     // INVALID ELEMENT: RAISE ISF so that it is later recognized!!!
diff --git a/lib/phpxmlrpc/PhpXmlRpc.php b/lib/phpxmlrpc/PhpXmlRpc.php
index 76ea4cd2742..c7c39eaa3e6 100644
--- a/lib/phpxmlrpc/PhpXmlRpc.php
+++ b/lib/phpxmlrpc/PhpXmlRpc.php
@@ -80,7 +80,7 @@ class PhpXmlRpc
     public static $xmlrpc_internalencoding = "UTF-8";
 
     public static $xmlrpcName = "XML-RPC for PHP";
-    public static $xmlrpcVersion = "4.8.0";
+    public static $xmlrpcVersion = "4.8.1";
 
     // let user errors start at 800
     public static $xmlrpcerruser = 800;
diff --git a/lib/phpxmlrpc/Value.php b/lib/phpxmlrpc/Value.php
index ec43fc140e9..e058957dc6f 100644
--- a/lib/phpxmlrpc/Value.php
+++ b/lib/phpxmlrpc/Value.php
@@ -262,7 +262,7 @@ class Value implements \Countable, \IteratorAggregate, \ArrayAccess
     }
 
     /**
-     * @param string typ
+     * @param string $typ
      * @param Value[]|mixed $val
      * @param string $charsetEncoding
      * @return string
@@ -304,12 +304,12 @@ class Value implements \Countable, \IteratorAggregate, \ArrayAccess
                     case static::$xmlrpcDateTime:
                         if (is_string($val)) {
                             $rs .= "<${typ}>${val}</${typ}>";
-                        } elseif (is_a($val, 'DateTime')) {
+                        } elseif (is_a($val, 'DateTime') || is_a($val, 'DateTimeInterface')) {
                             $rs .= "<${typ}>" . $val->format('Ymd\TH:i:s') . "</${typ}>";
                         } elseif (is_int($val)) {
-                            $rs .= "<${typ}>" . strftime("%Y%m%dT%H:%M:%S", $val) . "</${typ}>";
+                            $rs .= "<${typ}>" . date('Ymd\TH:i:s', $val) . "</${typ}>";
                         } else {
-                            // not really a good idea here: but what shall we output anyway? left for backward compat...
+                            // not really a good idea here: but what should we output anyway? left for backward compat...
                             $rs .= "<${typ}>${val}</${typ}>";
                         }
                         break;
diff --git a/lib/phpxmlrpc/readme_moodle.txt b/lib/phpxmlrpc/readme_moodle.txt
index 957c0836a72..ae13fbaaebe 100644
--- a/lib/phpxmlrpc/readme_moodle.txt
+++ b/lib/phpxmlrpc/readme_moodle.txt
@@ -16,7 +16,7 @@ To update:
 - Edit this file and update the release and commit details below.
 - Edit lib/thirdpartylibs.xml and update the information details too.
 
-Current version imported: 4.8.0 (39e37ed)
+Current version imported: 4.8.1 (c74cc31)
 
 Local changes:
  * readme_moodle.txt - this file ;-)
diff --git a/lib/thirdpartylibs.xml b/lib/thirdpartylibs.xml
index 460c3569d06..b89e2a30f9d 100644
--- a/lib/thirdpartylibs.xml
+++ b/lib/thirdpartylibs.xml
@@ -618,7 +618,7 @@ All rights reserved.</copyright>
     <location>phpxmlrpc</location>
     <name>phpxmlrpc</name>
     <description>A php library for building xml-rpc clients and servers</description>
-    <version>4.8.0</version>
+    <version>4.8.1</version>
     <license>BSD</license>
     <licenseversion>3-Clause</licenseversion>
     <repository>https://github.com/gggeek/phpxmlrpc</repository>