diff --git a/module/web/client.scm b/module/web/client.scm
index ab635c478..0c055abe9 100644
--- a/module/web/client.scm
+++ b/module/web/client.scm
@@ -218,7 +218,7 @@ host name without trailing dot."
     (with-https-proxy
      (let ((s (open-socket)))
        ;; Buffer input and output on this port.
-       (setvbuf s _IOFBF %http-receive-buffer-size)
+       (setvbuf s 'block %http-receive-buffer-size)
 
        (if https?
            (tls-wrap s (uri-host uri))