diff --git a/.env.example b/.env.example
index f9b81ff..c0279f5 100644
--- a/.env.example
+++ b/.env.example
@@ -13,6 +13,11 @@
 # forced to re-password in the browser at first sign-in. There is no secret to
 # put in this file for that -- set it in the app after the first `up -d`.
 
+# Host port SimHub is reachable on, e.g. http://<server>:8080. This maps to the
+# container's fixed internal port 3000, so you can change it freely without
+# touching the healthcheck. Defaults to 3000 if unset.
+HOST_PORT=3000
+
 # Runtime environment. Leave as "production" for real deployments.
 NODE_ENV=production
 
diff --git a/compose.yaml b/compose.yaml
index 170a378..e8204d3 100644
--- a/compose.yaml
+++ b/compose.yaml
@@ -29,9 +29,11 @@ services:
     init: true
 
     ports:
-      # "host:container" -- change the LEFT number to serve on a different host
-      # port. Quoted so YAML never reinterprets it (e.g. 22:22 as base-60).
-      - "3000:3000"
+      # "host:container". Set HOST_PORT in .env to serve on a different host
+      # port (defaults to 3000); the container port stays 3000 to match the
+      # image's healthcheck. Quoted so YAML never reinterprets it (e.g. 22:22
+      # as base-60).
+      - "${HOST_PORT:-3000}:3000"
 
     environment:
       # Production defaults. Override in .env if needed.