diff --git a/scheme/ftpd/ftpd.scm b/scheme/ftpd/ftpd.scm
index 31277e7..6531277 100644
--- a/scheme/ftpd/ftpd.scm
+++ b/scheme/ftpd/ftpd.scm
@@ -1173,7 +1173,7 @@
      (log (syslog-level debug) "closing data connection (226)")
      (register-reply! 226 "Closing data connection."))))
 
-(define *window-size* 4096)
+(define *window-size* 8192)
 
 (define (ensure-data-connection)
   (if (and (not (the-session-data-socket))