diff --git a/tests/php/Forms/HTMLEditor/HTMLEditorSanitiserTest.php b/tests/php/Forms/HTMLEditor/HTMLEditorSanitiserTest.php
index 3d5c3d5c6..d43dd9a5f 100644
--- a/tests/php/Forms/HTMLEditor/HTMLEditorSanitiserTest.php
+++ b/tests/php/Forms/HTMLEditor/HTMLEditorSanitiserTest.php
@@ -11,9 +11,9 @@ use SilverStripe\View\Parsers\HTMLValue;
 class HTMLEditorSanitiserTest extends FunctionalTest
 {
 
-    public function testSanitisation()
+    public function provideSanitise(): array
     {
-        $tests = [
+        return [
             [
                 'p,strong',
                 '<p>Leave Alone</p><div>Strip parent<strong>But keep children</strong> in order</div>',
@@ -129,13 +129,20 @@ class HTMLEditorSanitiserTest extends FunctionalTest
                 'XSS vulnerable attributes starting with on or style are removed via configuration'
             ],
         ];
+    }
 
-        $config = HTMLEditorConfig::get('htmleditorsanitisertest');
-
-        foreach ($tests as $test) {
-            list($validElements, $input, $output, $desc) = $test;
-
-            $config->setOptions(['valid_elements' => $validElements]);
+    /**
+     * @dataProvider provideSanitise
+     */
+    public function testSanitisation(string $validElements, string $input, string $output, string $desc): void
+    {
+        foreach (['valid_elements', 'extended_valid_elements'] as $configType) {
+            $config = HTMLEditorConfig::get('htmleditorsanitisertest_' . $configType);
+            $config->setOptions([$configType => $validElements]);
+            // Remove default valid elements if we're testing extended valid elements
+            if ($configType !== 'valid_elements') {
+                $config->setOptions(['valid_elements' => '']);
+            }
             $sanitiser = new HtmlEditorSanitiser($config);
 
             $value = 'noopener noreferrer';
@@ -144,12 +151,13 @@ class HTMLEditorSanitiserTest extends FunctionalTest
             } elseif (strpos($desc ?? '', 'link_rel_value is null') !== false) {
                 $value = null;
             }
-            Config::inst()->set(HTMLEditorSanitiser::class, 'link_rel_value', $value);
+
+            HTMLEditorSanitiser::config()->set('link_rel_value', $value);
 
             $htmlValue = HTMLValue::create($input);
             $sanitiser->sanitise($htmlValue);
 
-            $this->assertEquals($output, $htmlValue->getContent(), $desc);
+            $this->assertEquals($output, $htmlValue->getContent(), "{$desc} - using config type: {$configType}");
         }
     }
 }