diff --git a/README.md b/README.md
index 8020d2f..ee4ba7a 100644
--- a/README.md
+++ b/README.md
@@ -78,11 +78,21 @@ docker compose up --build
 DOCKER_BUILDKIT=1 docker build --tag rails-on-docker --file production.Dockerfile . --load
 ```
 
+Test the image can be used and Rails starts up, use a fake key for testing purposes only:
+```
+docker run --rm --env SECRET_KEY_BASE=dummy rails-on-docker
+```
+
 ### With legacy builder (no BuildKit)
 ```
 docker build --tag rails-on-docker --file production.Dockerfile .
 ```
 
+Test the image can be used and Rails starts up, use a fake key for testing purposes only:
+```
+docker run --rm --env SECRET_KEY_BASE=dummy rails-on-docker
+```
+
 ## Deployment
 
 This app can be hosted wherever Ruby is supported and PostgreSQL databases can be provisioned.
diff --git a/production.Dockerfile b/production.Dockerfile
index 7e6f56f..9a18842 100644
--- a/production.Dockerfile
+++ b/production.Dockerfile
@@ -83,6 +83,5 @@ HEALTHCHECK --interval=5s --timeout=3s --start-period=0s --start-interval=5s --r
 
 # Start the server by default, this can be overwritten at runtime
 EXPOSE 3000
-EXPOSE 10000
 # CMD ["./bin/rails", "server"]
 CMD ["bundle", "exec", "puma", "-C", "config/puma.rb"]
diff --git a/render.yaml b/render.yaml
index e32c5f3..529afb9 100644
--- a/render.yaml
+++ b/render.yaml
@@ -17,6 +17,8 @@ services:
     numInstances: 1
     healthCheckPath: /up
     envVars:
+      - key: PORT
+        value: 3000
       - key: DATABASE_URL
         fromDatabase:
           name: mysite