diff --git a/README.md b/README.md
index c4a629e..919d762 100644
--- a/README.md
+++ b/README.md
@@ -78,6 +78,8 @@ In this example, the `my-nginx-proxy` container will be connected to `my-network
 
 If you would like to connect to your backend using HTTPS instead of HTTP, set `VIRTUAL_PROTO=https` on the backend container.
 
+> Note: If you use `VIRTUAL_PROTO=https` and your backend container exposes port 80 and 443, `nginx-proxy` will use HTTPS on port 80.  This is almost certainly not what you want, so you should also include `VIRTUAL_PORT=443`.
+
 ### uWSGI Backends
 
 If you would like to connect to uWSGI backend, set `VIRTUAL_PROTO=uwsgi` on the