diff --git a/TrackerHostname.php b/TrackerHostname.php
index aeffe55..17b973e 100644
--- a/TrackerHostname.php
+++ b/TrackerHostname.php
@@ -15,7 +15,7 @@ class TrackerHostname extends Plugin
     public function registerEvents()
     {
         return array(
-            'Piwik.getJavascriptCode' => array(
+            'Tracker.getJavascriptCode' => array(
                 'function' => 'customizeTrackerHostname',
                 'before' => true,
             ),
diff --git a/plugin.json b/plugin.json
index c9e5779..aab0c82 100644
--- a/plugin.json
+++ b/plugin.json
@@ -4,7 +4,7 @@
     "version": "0.1.0",
     "theme": false,
     "require": {
-        "piwik": ">=3.13.0-stable,<5.0.0-b1"
+        "piwik": ">=4.0.0-b1,<5.0.0-b1"
     },
     "authors": [
         {