diff --git a/docker-compose.yml b/docker-compose.yml
index 86dab3f..be9df63 100644
--- a/docker-compose.yml
+++ b/docker-compose.yml
@@ -2,13 +2,14 @@ services:
   pr-helper:
     build: .
     ports:
-      - "8080:8080"
+      - "${PORT:-8080}:8080"
     volumes:
       - pr-helper-data:/app/data
     env_file:
       - .env
     environment:
       - GIN_MODE=release
+      - PORT=8080  # internal container port; external port set by .env PORT
       # MYSQL_HOST in .env should point to your external MySQL
       # Use host.docker.internal to reach the host machine from inside Docker
     extra_hosts: