diff --git a/library/Icinga/Web/View/helpers/url.php b/library/Icinga/Web/View/helpers/url.php
index 3056d3644..e3d23a359 100644
--- a/library/Icinga/Web/View/helpers/url.php
+++ b/library/Icinga/Web/View/helpers/url.php
@@ -103,7 +103,7 @@ $this->addHelperFunction('attributeToString', function ($key, $value)
     return sprintf(
         '%s="%s"',
         $key,
-        $value
+        $this->escape($value)
     );
 });