diff --git a/Classes/CacheManager.php b/Classes/CacheManager.php
index fa4162c..5389a4c 100644
--- a/Classes/CacheManager.php
+++ b/Classes/CacheManager.php
@@ -86,7 +86,7 @@ public function execute(): void
         }
 
         // initialize all connections
-        $active = null;
+        $active = 0;
         do {
             $multiExecResult = curl_multi_exec($multiHandle, $active);
             $this->logger->debug('status init: ' . $multiExecResult);
diff --git a/composer.json b/composer.json
index 41e266c..bc0a1e4 100644
--- a/composer.json
+++ b/composer.json
@@ -6,7 +6,7 @@
   "license": ["GPL-2.0+"],
   "keywords": ["TYPO3 CMS", "Purge"],
   "require": {
-    "typo3/cms-core": "^11.5"
+    "typo3/cms-core": "^11.5 || ^12.4"
   },
   "autoload": {
     "psr-4": {
diff --git a/ext_emconf.php b/ext_emconf.php
index 6f51999..22b81af 100644
--- a/ext_emconf.php
+++ b/ext_emconf.php
@@ -4,12 +4,12 @@
     'title' => 'Cache Purger',
     'description' => 'Purge cached URLs within Varnish instances',
     'category' => 'misc',
-    'version' => '2.0.0',
+    'version' => '3.0.0',
     'state' => 'stable',
     'clearCacheOnLoad' => 0,
     'constraints' => [
         'depends' => [
-            'typo3' => '11.5.0-11.5.99',
+            'typo3' => '11.5.0-12.4.99',
         ],
         'conflicts' => [],
         'suggests' => [],
diff --git a/ext_localconf.php b/ext_localconf.php
index d166235..2bd2b6f 100644
--- a/ext_localconf.php
+++ b/ext_localconf.php
@@ -1,6 +1,6 @@
 <?php
 
-defined('TYPO3_MODE') || die();
+defined('TYPO3') || die();
 
 call_user_func(
     static function (string $extensionKey): void {