diff --git a/rainloop/v/0.0.0/app/libraries/RainLoop/Service.php b/rainloop/v/0.0.0/app/libraries/RainLoop/Service.php
index 7fc312c9c..beac9fe02 100644
--- a/rainloop/v/0.0.0/app/libraries/RainLoop/Service.php
+++ b/rainloop/v/0.0.0/app/libraries/RainLoop/Service.php
@@ -212,7 +212,7 @@ class Service
 
 			$sResult .= ']-->';
 		}
-		else
+		else if (!headers_sent())
 		{
 			\header('X-XSS-Protection: 1; mode=block');
 		}