diff --git a/Services/HtmlSanitiser.php b/Services/HtmlSanitiser.php
index c26f93b..bfad7de 100644
--- a/Services/HtmlSanitiser.php
+++ b/Services/HtmlSanitiser.php
@@ -97,20 +97,6 @@ class HtmlSanitiser
         $config->set('HTML.Nofollow', true);
         $config->set('HTML.TargetNoopener', true);
 
-        // Disable cache and set definition ID for custom HTML definitions
-        $config->set('Cache.DefinitionImpl', null);
-        $config->set('HTML.DefinitionID', 'core-content-html5');
-        $config->set('HTML.DefinitionRev', 1);
-
-        // Register HTML5 elements that HTMLPurifier doesn't know about
-        if ($def = $config->maybeGetRawHTMLDefinition()) {
-            $def->addElement('section', 'Block', 'Flow', 'Common');
-            $def->addElement('article', 'Block', 'Flow', 'Common');
-            $def->addElement('figure', 'Block', 'Flow', 'Common');
-            $def->addElement('figcaption', 'Inline', 'Flow', 'Common');
-            $def->addElement('mark', 'Inline', 'Inline', 'Common');
-        }
-
         // Safe URI schemes only
         $config->set('URI.AllowedSchemes', [
             'http' => true,
@@ -123,6 +109,22 @@ class HtmlSanitiser
         $config->set('URI.DisableExternalResources', false);
         $config->set('URI.DisableResources', false);
 
+        // Disable cache and set definition ID for custom HTML definitions
+        $config->set('Cache.DefinitionImpl', null);
+        $config->set('HTML.DefinitionID', 'core-content-html5');
+        $config->set('HTML.DefinitionRev', 1);
+
+        // Register HTML5 elements that HTMLPurifier doesn't know about
+        // NOTE: maybeGetRawHTMLDefinition() finalizes the config — all
+        // $config->set() calls must come before this point.
+        if ($def = $config->maybeGetRawHTMLDefinition()) {
+            $def->addElement('section', 'Block', 'Flow', 'Common');
+            $def->addElement('article', 'Block', 'Flow', 'Common');
+            $def->addElement('figure', 'Block', 'Flow', 'Common');
+            $def->addElement('figcaption', 'Inline', 'Flow', 'Common');
+            $def->addElement('mark', 'Inline', 'Inline', 'Common');
+        }
+
         $this->purifier = new HTMLPurifier($config);
     }
 
diff --git a/tests/TestCase.php b/tests/TestCase.php
index 1434eee..48fcd42 100644
--- a/tests/TestCase.php
+++ b/tests/TestCase.php
@@ -30,28 +30,7 @@ abstract class TestCase extends BaseTestCase
 
         // Stub external dependencies not available in test environment
         if (! class_exists(\Plug\Cdn\CdnManager::class)) {
-            $app->bind(\Core\Mod\Content\Services\CdnPurgeService::class, fn () => new class
-            {
-                public function isEnabled(): bool
-                {
-                    return false;
-                }
-
-                public function purgeContent($content)
-                {
-                    return null;
-                }
-
-                public function purgeUrls(array $urls)
-                {
-                    return null;
-                }
-
-                public function purgeWorkspace(string $uuid)
-                {
-                    return null;
-                }
-            });
+            $app->bind(\Core\Mod\Content\Services\CdnPurgeService::class, fn () => \Mockery::mock(\Core\Mod\Content\Services\CdnPurgeService::class)->shouldIgnoreMissing());
         }
     }
 }