diff --git a/fastcgi.scm b/fastcgi.scm
index aa89b0d..b678f0e 100644
--- a/fastcgi.scm
+++ b/fastcgi.scm
@@ -242,7 +242,8 @@
     (let loop ()
       ;; Wait for a connection from the webserver.
       (fcgi-accept-request! req)
-      (and-let* (((callback
+      (and-let* ((_ (fcgi-request-out req))
+                 ((callback
                    (wrap-in-stream (fcgi-request-in req))
                    (wrap-out-stream (fcgi-request-out req))
                    (wrap-out-stream (fcgi-request-error req))