diff --git a/lib/phpmailer/README_MOODLE.txt b/lib/phpmailer/README_MOODLE.txt
index d87a202780a..6b176304c4b 100644
--- a/lib/phpmailer/README_MOODLE.txt
+++ b/lib/phpmailer/README_MOODLE.txt
@@ -21,4 +21,11 @@ UPGRADING.md
 composer.json
 get_oauth_token.php
 phpdoc.dist.xml
-travis.phpunit.xml.dist
\ No newline at end of file
+travis.phpunit.xml.dist
+
+Local changes (to verify/apply with new imports):
+
+- MDL-63967: PHP 7.3 compatibility.
+    lib/phpmailer/src/PHPMailer.php: FILTER_FLAG_HOST_REQUIRED is deprecated and
+    implied with FILTER_VALIDATE_URL. This was fixed upstream by
+    https://github.com/PHPMailer/PHPMailer/pull/1551
diff --git a/lib/phpmailer/src/PHPMailer.php b/lib/phpmailer/src/PHPMailer.php
index b710ab809f9..b5b98652054 100644
--- a/lib/phpmailer/src/PHPMailer.php
+++ b/lib/phpmailer/src/PHPMailer.php
@@ -3578,7 +3578,7 @@ class PHPMailer
             //Is it a valid IPv4 address?
             return (bool) filter_var($host, FILTER_VALIDATE_IP, FILTER_FLAG_IPV4);
         }
-        if (filter_var('http://' . $host, FILTER_VALIDATE_URL, FILTER_FLAG_HOST_REQUIRED)) {
+        if (filter_var('http://' . $host, FILTER_VALIDATE_URL)) {
             //Is it a syntactically valid hostname?
             return true;
         }
diff --git a/lib/typo3/class.t3lib_div.php b/lib/typo3/class.t3lib_div.php
index c5012a675f3..243db4d9e87 100644
--- a/lib/typo3/class.t3lib_div.php
+++ b/lib/typo3/class.t3lib_div.php
@@ -1527,7 +1527,7 @@ final class t3lib_div {
 		require_once(PATH_typo3 . 'contrib/idna/idna_convert.class.php');
 		$IDN = new idna_convert(array('idn_version' => 2008));
 
-		return (filter_var($IDN->encode($url), FILTER_VALIDATE_URL, FILTER_FLAG_SCHEME_REQUIRED) !== FALSE);
+		return (filter_var($IDN->encode($url), FILTER_VALIDATE_URL) !== FALSE);
 	}
 
 
diff --git a/lib/typo3/readme_moodle.txt b/lib/typo3/readme_moodle.txt
index 246aebfe16b..cb1e332561b 100644
--- a/lib/typo3/readme_moodle.txt
+++ b/lib/typo3/readme_moodle.txt
@@ -8,4 +8,11 @@ Procedure:
 2/ copy csconvtbl/*, unidata/* and all other necessary files we use
 3/ run our phpunit tests with and without mbstring PHP extension
 
+Local changes (to verify/apply with new imports):
+
+- MDL-63967: PHP 7.3 compatibility.
+    lib/typo3/class.t3lib_div.php: FILTER_FLAG_SCHEME_REQUIRED is deprecated and
+    implied with FILTER_VALIDATE_URL. This is fixed upstream since Typo 6, with
+    the file class now under \TYPO3\CMS\Core\Utility\GeneralUtility.
+
 skodak, stronk7, moodler