diff --git a/docs/networking/port-management.md b/docs/networking/port-management.md
index 8d4648483..1b56e0546 100644
--- a/docs/networking/port-management.md
+++ b/docs/networking/port-management.md
@@ -15,6 +15,8 @@ In Dokku 0.5.0, port proxying was decoupled from the `nginx-vhosts` plugin into
 ## Usage
 
 > Warning: Mapping alternative ports may conflict with the active firewall installed on your server or hosting provider. Such software includes - but is not limited to - AWS Security Groups, iptables, and UFW. Please consult the documentation for those softwares as applicable.
+>
+> Users should also avoid setting the `PORT` environment variable. Dokku will use port mappings to set this value. Overridng this manually may cause issues in application routing.
 
 > New as of 0.6.0