diff --git a/src/wp-includes/ms-files.php b/src/wp-includes/ms-files.php
index 87fa70f4b9..e5c1db3f89 100644
--- a/src/wp-includes/ms-files.php
+++ b/src/wp-includes/ms-files.php
@@ -80,3 +80,4 @@ if ( ( $client_last_modified && $client_etag )
 
 // If we made it this far, just serve the file
 readfile( $file );
+flush();