diff --git a/lib/kolab_client_output.php b/lib/kolab_client_output.php
--- a/lib/kolab_client_output.php
+++ b/lib/kolab_client_output.php
@@ -145,7 +145,7 @@
             $this->tpl->assign($name, $value);
         }
 
-        $script = '';
+        $script = array();
 
         if (!empty($this->env)) {
             $script[] = 'kadm.env = ' . json_encode($this->env) . ';';
@@ -171,7 +171,7 @@
         }
 
         $this->tpl->assign('skin_path', 'skins/' . $this->skin . '/');
-        if ($script) {
+        if (!empty($script)) {
             $script = "<script type=\"text/javascript\">\n" . implode("\n", $script) . "\n</script>";
             $this->tpl->assign('script', $script);
         }