diff --git a/composer.json b/composer.json
index b9fda4abe4..88ce28ee0d 100644
--- a/composer.json
+++ b/composer.json
@@ -35,6 +35,7 @@
     },
     "require": {
         "php": ">=7.2.0",
+        "ext-libxml": "*",
         "ext-simplexml": "*",
         "ext-tokenizer": "*",
         "ext-xmlwriter": "*"
diff --git a/requirements.php b/requirements.php
index 2250b4a4de..b6cf7f9be2 100644
--- a/requirements.php
+++ b/requirements.php
@@ -41,6 +41,7 @@ function checkRequirements()
 
     $requiredExtensions = array(
         'tokenizer',
+        'libxml',
         'xmlwriter',
         'SimpleXML',
     );
diff --git a/scripts/BuildRequirementsCheckMatrix.php b/scripts/BuildRequirementsCheckMatrix.php
index c86723433c..a60c143415 100644
--- a/scripts/BuildRequirementsCheckMatrix.php
+++ b/scripts/BuildRequirementsCheckMatrix.php
@@ -82,7 +82,7 @@ public function getBuilds()
      */
     private function getValidBuilds()
     {
-        $extensions = ['minimal' => 'none, tokenizer, xmlwriter, SimpleXML'];
+        $extensions = ['minimal' => 'none, tokenizer, libxml, xmlwriter, SimpleXML'];
 
         $builds = [];
         foreach ($this->validPhp as $php) {
@@ -145,10 +145,10 @@ private function getInvalidPHPBuilds()
     private function getMissingExtensionsBuilds()
     {
         $extensions = [
-            'missing tokenizer'     => 'none, xmlwriter, SimpleXML',
-            'missing xmlwriter'     => ':xmlwriter',
-            'missing SimpleXML'     => ':SimpleXML',
-            'missing both XML exts' => 'none, tokenizer',
+            'missing tokenizer'    => 'none, xmlwriter, SimpleXML',
+            'missing xmlwriter'    => ':xmlwriter',
+            'missing SimpleXML'    => ':SimpleXML',
+            'missing all XML exts' => 'none, tokenizer',
         ];
 
         $builds = [];