diff --git a/inc/pageutils.php b/inc/pageutils.php
index 4229c60cd50dffc6217ae5685b79fde7edbb1da2..6ccc49c7f0c09a0b3d7402629946a33cd85ab551 100644
--- a/inc/pageutils.php
+++ b/inc/pageutils.php
@@ -538,6 +538,9 @@ function http_conditionalRequest($timestamp){
 
   // Nothing has changed since their last request - serve a 304 and exit
   header('HTTP/1.0 304 Not Modified');
+
+  // don't produce output, even if compression is on
+  ob_end_clean();
   exit;
 }