diff --git a/web.scm b/web.scm
index 411a6cc..e76f8b2 100644
--- a/web.scm
+++ b/web.scm
@@ -4,4 +4,4 @@
  (lambda (request request-body)
   (values '((content-type . (text/plain)))
    (process-line (utf8->string request-body))))
- 'http '(#:port 7183))
+ 'http `(#:port ,(string->number (getenv "PORT"))))