diff --git a/core/Plugin.php b/core/Plugin.php
index e938a9a1fef94abf3ebbd8a80041fc629842297b..a706469573ba96dbffff60fd3b4045391a559632 100644
--- a/core/Plugin.php
+++ b/core/Plugin.php
@@ -337,6 +337,8 @@ class Plugin
         $files = Filesystem::globr(PIWIK_INCLUDE_PATH . '/plugins/' . $this->pluginName .'/' . $directoryWithinPlugin, '*.php');
 
         foreach ($files as $file) {
+            require_once $file;
+
             $klassName = sprintf('Piwik\\Plugins\\%s\\%s\\%s', $this->pluginName, $directoryWithinPlugin, basename($file, '.php'));
 
             if (!class_exists($klassName)) {