diff --git a/Dockerfile b/Dockerfile
index 8ccfb27..73988fa 100644
--- a/Dockerfile
+++ b/Dockerfile
@@ -32,7 +32,6 @@ COPY --from=builder /src/bin/upaasd /app/upaasd
 RUN mkdir -p /var/lib/upaas
 
 ENV UPAAS_DATA_DIR=/var/lib/upaas
-ENV UPAAS_PORT=8080
 
 EXPOSE 8080
 
diff --git a/README.md b/README.md
index dd22758..e9623a4 100644
--- a/README.md
+++ b/README.md
@@ -156,7 +156,7 @@ Environment variables:
 
 | Variable | Description | Default |
 |----------|-------------|---------|
-| `UPAAS_PORT` | HTTP listen port | 8080 |
+| `PORT` | HTTP listen port | 8080 |
 | `UPAAS_DATA_DIR` | Data directory for SQLite and keys | ./data |
 | `UPAAS_DOCKER_HOST` | Docker socket path | unix:///var/run/docker.sock |
 | `DEBUG` | Enable debug logging | false |
diff --git a/docker-compose.yml b/docker-compose.yml
index da269db..e06e49f 100644
--- a/docker-compose.yml
+++ b/docker-compose.yml
@@ -7,8 +7,7 @@ services:
     volumes:
       - /var/run/docker.sock:/var/run/docker.sock
       - upaas-data:/var/lib/upaas
-    environment:
-      - UPAAS_PORT=8080
+    # environment:
       # Optional: uncomment to enable debug logging
       # - DEBUG=true
       # Optional: Sentry error reporting
diff --git a/internal/config/config.go b/internal/config/config.go
index 4881983..f442fdd 100644
--- a/internal/config/config.go
+++ b/internal/config/config.go
@@ -89,6 +89,9 @@ func setupViper(name string) {
 	viper.AutomaticEnv()
 
 	// Defaults
+	// PORT is not prefixed with UPAAS_ for compatibility
+	_ = viper.BindEnv("PORT", "PORT")
+
 	viper.SetDefault("PORT", defaultPort)
 	viper.SetDefault("DEBUG", false)
 	viper.SetDefault("DATA_DIR", "./data")