diff --git a/webdav.php b/webdav.php
index 76d3062767..0d8b6aea6a 100644
--- a/webdav.php
+++ b/webdav.php
@@ -90,7 +90,8 @@ catch (egw_exception_no_permission_app $e)
 $headertime = microtime(true);
 
 // switch of output buffering (switched on in header), as otherwise we run against memory_limit, for big files
-ob_end_flush();
+// only do it if no output_handler is set in php.ini, as at least with zlib.output_handler it stalls ...
+if (!ini_get('output_handler')) ob_end_flush();
 
 $webdav_server = new vfs_webdav_server();
 $webdav_server->ServeRequest();