diff --git a/internal/server/server.go b/internal/server/server.go
index 49bcd50..0bd8951 100644
--- a/internal/server/server.go
+++ b/internal/server/server.go
@@ -6,6 +6,7 @@ import (
 	"errors"
 	"fmt"
 	"log/slog"
+	"net"
 	"net/http"
 	"os"
 	"os/signal"
@@ -39,6 +40,7 @@ type Params struct {
 	Config     *config.Config
 	Middleware *middleware.Middleware
 	Handlers   *handlers.Handlers
+	Shutdowner fx.Shutdowner
 }
 
 // Server is the main HTTP server.
@@ -66,7 +68,7 @@ func New(
 	}
 
 	lifecycle.Append(fx.Hook{
-		OnStart: func(_ context.Context) error {
+		OnStart: func(ctx context.Context) error {
 			srv.startupTime = time.Now()
 
 			// Build the router before OnStart returns, so srv can
@@ -78,9 +80,7 @@ func New(
 			// A closed stdout or stderr must not end the process.
 			signal.Ignore(syscall.SIGPIPE)
 
-			srv.startHTTP()
-
-			return nil
+			return srv.startHTTP(ctx)
 		},
 		OnStop: func(ctx context.Context) error {
 			srv.cleanShutdown(ctx)
@@ -162,15 +162,23 @@ func (srv *Server) configure() {
 	// Server configuration placeholder.
 }
 
-// startHTTP creates the HTTP server and serves it from a new
-// goroutine. srv.httpServer is set before that goroutine
-// starts and never changes, so it and cleanShutdown read it
-// without a lock.
-func (srv *Server) startHTTP() {
+// startHTTP binds the HTTP listen address, so that a port
+// that is taken fails startup, then serves the HTTP server
+// from a new goroutine. srv.httpServer is set before that
+// goroutine starts and never changes, so it and cleanShutdown
+// read it without a lock.
+func (srv *Server) startHTTP(ctx context.Context) error {
 	listenAddr := fmt.Sprintf(
 		":%d", srv.params.Config.Port,
 	)
 
+	var listenConfig net.ListenConfig
+
+	listener, err := listenConfig.Listen(ctx, "tcp", listenAddr)
+	if err != nil {
+		return fmt.Errorf("http listen: %w", err)
+	}
+
 	srv.httpServer = &http.Server{ //nolint:exhaustruct // optional fields
 		Addr:           listenAddr,
 		ReadTimeout:    httpReadTimeout,
@@ -179,16 +187,30 @@ func (srv *Server) startHTTP() {
 		Handler:        srv,
 	}
 
-	go srv.serveUntilShutdown()
+	go func() {
+		srv.serveUntilShutdown(listener)
+	}()
+
+	return nil
 }
 
-func (srv *Server) serveUntilShutdown() {
+// serveUntilShutdown serves the HTTP server on listener until
+// cleanShutdown stops it. If serving fails before then, it
+// stops the app with exit code 1.
+func (srv *Server) serveUntilShutdown(listener net.Listener) {
 	srv.log.Info(
 		"http begin listen", "listenaddr", srv.httpServer.Addr,
 	)
 
-	err := srv.httpServer.ListenAndServe()
-	if err != nil && !errors.Is(err, http.ErrServerClosed) {
-		srv.log.Error("listen error", "error", err)
+	err := srv.httpServer.Serve(listener)
+	if errors.Is(err, http.ErrServerClosed) {
+		return
+	}
+
+	srv.log.Error("listen error", "error", err)
+
+	err = srv.params.Shutdowner.Shutdown(fx.ExitCode(1))
+	if err != nil {
+		srv.log.Error("shutdown failed", "error", err)
 	}
 }
diff --git a/internal/server/server_test.go b/internal/server/server_test.go
index c740ba1..71dfeb4 100644
--- a/internal/server/server_test.go
+++ b/internal/server/server_test.go
@@ -6,6 +6,7 @@ import (
 	"net"
 	"net/http"
 	"strconv"
+	"strings"
 	"testing"
 	"time"
 
@@ -103,15 +104,68 @@ func TestStopWaitsForRequestInProgress(t *testing.T) {
 	}
 }
 
-// startApp starts the server with the dependencies
-// cmd/neoircd gives it, on a fresh in-memory database, with
-// the HTTP server listening on port.
+// TestStartFailsWhenHTTPPortIsTaken checks that starting the
+// app, which runs the start hook server.New registers,
+// returns an error naming the HTTP listen address when
+// something else is already listening on its port.
+func TestStartFailsWhenHTTPPortIsTaken(t *testing.T) {
+	t.Parallel()
+
+	var listenConfig net.ListenConfig
+
+	taken, err := listenConfig.Listen(t.Context(), "tcp", ":0")
+	if err != nil {
+		t.Fatalf("listen: %v", err)
+	}
+
+	t.Cleanup(func() { _ = taken.Close() })
+
+	tcpAddr, ok := taken.Addr().(*net.TCPAddr)
+	if !ok {
+		t.Fatalf("listener address %v is not TCP", taken.Addr())
+	}
+
+	app, _, _ := newApp(t, tcpAddr.Port)
+
+	err = app.Start(t.Context())
+	if err == nil {
+		app.RequireStop()
+		t.Fatal("the app started while its HTTP port was taken")
+	}
+
+	listenAddr := fmt.Sprintf(":%d", tcpAddr.Port)
+	if !strings.Contains(err.Error(), listenAddr) {
+		t.Errorf("start error %q does not name %s", err, listenAddr)
+	}
+}
+
+// startApp starts the app newApp builds, with the HTTP server
+// listening on port.
 func startApp(
 	t *testing.T,
 	port int,
 ) (*fxtest.App, *broker.Broker, *db.Database) {
 	t.Helper()
 
+	app, brk, database := newApp(t, port)
+
+	app.RequireStart()
+
+	// Stops the app if the test ends before stopping it.
+	t.Cleanup(app.RequireStop)
+
+	return app, brk, database
+}
+
+// newApp builds, without starting it, an app that runs the
+// server with the dependencies cmd/neoircd gives it, on a
+// fresh in-memory database, with the HTTP port set to port.
+func newApp(
+	t *testing.T,
+	port int,
+) (*fxtest.App, *broker.Broker, *db.Database) {
+	t.Helper()
+
 	var (
 		brk      *broker.Broker
 		database *db.Database
@@ -148,11 +202,6 @@ func startApp(
 		fx.Populate(&brk, &database),
 	)
 
-	app.RequireStart()
-
-	// Stops the app if the test ends before stopping it.
-	t.Cleanup(app.RequireStop)
-
 	return app, brk, database
 }