diff --git a/formats/MrssFormat.php b/formats/MrssFormat.php
index 7ea9756f..39d248d2 100644
--- a/formats/MrssFormat.php
+++ b/formats/MrssFormat.php
@@ -10,7 +10,7 @@ class MrssFormat extends FormatAbstract {
 		$httpHost = isset($_SERVER['HTTP_HOST']) ? $_SERVER['HTTP_HOST'] : '';
 		$httpInfo = isset($_SERVER['PATH_INFO']) ? $_SERVER['PATH_INFO'] : '';
 
-		$serverRequestUri = $this->xml_encode($_SERVER['REQUEST_URI']);
+		$serverRequestUri = isset($_SERVER['REQUEST_URI']) ? $this->xml_encode($_SERVER['REQUEST_URI']) : '';
 
 		$extraInfos = $this->getExtraInfos();
 		$title = $this->xml_encode($extraInfos['name']);