diff --git a/gulliver/system/class.bootstrap.php b/gulliver/system/class.bootstrap.php
index f2250c7c9..e2c1ca36f 100644
--- a/gulliver/system/class.bootstrap.php
+++ b/gulliver/system/class.bootstrap.php
@@ -806,6 +806,7 @@ class Bootstrap
     public static function streamCSSBigFile($filename)
     {
         header('Content-Type: text/css');
+        header('X-Content-Type-Options: nosniff');
 
         //First get Skin info
         $filenameParts = explode("-", $filename);
@@ -969,7 +970,7 @@ class Bootstrap
             header('Content-Disposition: attachment; filename="' . $downloadFileName . '"');
         }
         header('Content-Type: ' . $contentType);
-
+        header('X-Content-Type-Options: nosniff');
         // if userAgent (BROWSER) is MSIE we need special headers to avoid MSIE
         // behaivor.
         $userAgent = strtolower($_SERVER ['HTTP_USER_AGENT']);
diff --git a/gulliver/system/class.g.php b/gulliver/system/class.g.php
index e72afb64f..05653aee3 100644
--- a/gulliver/system/class.g.php
+++ b/gulliver/system/class.g.php
@@ -947,7 +947,7 @@ class G
     public static function streamCSSBigFile($filename)
     {
         header('Content-Type: text/css');
-
+        header('X-Content-Type-Options: nosniff');
         //First get Skin info
         $filenameParts = explode("-", $filename);
         $skinName = $filenameParts[0];
@@ -1252,7 +1252,7 @@ class G
             header('Content-Disposition: inline; filename="' . $downloadFileName . '"');
         }
         header('Content-Type: ' . $contentType);
-
+        header('X-Content-Type-Options: nosniff');
         //if userAgent (BROWSER) is MSIE we need special headers to avoid MSIE behaivor.
         $userAgent = strtolower($_SERVER['HTTP_USER_AGENT']);
         if (preg_match("/msie/i", $userAgent)) {