diff --git a/src/Url.php b/src/Url.php
index c50954a..07aec97 100644
--- a/src/Url.php
+++ b/src/Url.php
@@ -547,6 +547,8 @@ class Url {
     if (is_array($value)) {
       foreach($value as $v)
         $url = self :: add_url_parameter($url, $parameter."[]", $v);
+      if (empty($value))
+        $url = self :: add_url_parameter($url, $parameter, "");
       return $url;
     }
     if (strpos($url, '?') === false)