diff --git a/README.md b/README.md
index e5ac1c5..23b7cb2 100644
--- a/README.md
+++ b/README.md
@@ -47,18 +47,19 @@ matrixbox app /path/to/matrixbox/apps/clock
 Terminal 2, watch it:
 
 ```sh
-matrixbox simulator --connect ws://127.0.0.1:9191
+matrixbox simulator
 ```
 
-The renderer waits for the simulator if it isn't up yet, and reconnects
-automatically if you stop it to switch apps, so you can just leave it
-running.
+Connects to `ws://127.0.0.1:9191` by default, matching `matrixbox app`'s
+own default port — use `--connect <url>` if you changed it. The renderer
+waits for the simulator if it isn't up yet, and reconnects automatically
+if you stop it to switch apps, so you can just leave it running.
 
 While an app is running, its real settings page is served too, at
 `http://127.0.0.1:8080/` (override with `MATRIXBOX_SIMULATOR_HTTP_PORT`).
 
-No app running yet? `matrixbox simulator` on its own draws an animated
-demo pattern, a quick way to check it's working.
+No app running yet? `matrixbox simulator --demo` draws an animated demo
+pattern instead, a quick way to check it's working.
 
 ## Panel sizes
 
diff --git a/matrixbox_simulator/term/run_simulator.py b/matrixbox_simulator/term/run_simulator.py
index aabfec6..4db24e0 100644
--- a/matrixbox_simulator/term/run_simulator.py
+++ b/matrixbox_simulator/term/run_simulator.py
@@ -2,12 +2,12 @@
 
 Usage:
 
-    matrixbox simulator --connect ws://127.0.0.1:9191
+    matrixbox simulator
 
-No simulator running? Omit --connect to run an animated demo pattern
-instead:
+Connects to ws://127.0.0.1:9191 by default; --connect overrides that.
+No simulator running? --demo draws an animated demo pattern instead:
 
-    matrixbox simulator
+    matrixbox simulator --demo
 """
 
 import argparse
@@ -39,6 +39,10 @@
 # simulator restarting to switch apps).
 RECONNECT_DELAY_SECONDS = 0.3
 
+# matrixbox app's own --ws-port default: matches so the common case, one
+# app and one renderer on the same machine, needs no --connect at all.
+DEFAULT_CONNECT_URL = "ws://127.0.0.1:9191"
+
 
 def build_parser(
     parser: argparse.ArgumentParser | None = None,
@@ -48,10 +52,15 @@ def build_parser(
 
     parser.add_argument(
         "--connect",
-        default=None,
-        help="Frame server to connect to, e.g. ws://127.0.0.1:9191. Omit to run "
-        "an animated demo pattern instead, useful for exercising the renderer "
-        "without the simulator running.",
+        default=DEFAULT_CONNECT_URL,
+        help=f"Frame server to connect to (default: {DEFAULT_CONNECT_URL}).",
+    )
+    parser.add_argument(
+        "--demo",
+        action="store_true",
+        help="Draw an animated demo pattern instead of connecting to a frame "
+        "server, useful for exercising the renderer without the simulator "
+        "running.",
     )
     parser.add_argument(
         "--device",
@@ -113,12 +122,12 @@ def is_running() -> bool:
     renderer = TerminalRenderer()
     try:
         with _key_listener(renderer):
-            if args.connect:
+            if args.demo:
+                run_demo(args.width, args.height, tiles, args.fps, renderer, is_running)
+            else:
                 run_connected(
                     args.connect, args.width, args.height, tiles, renderer, is_running
                 )
-            else:
-                run_demo(args.width, args.height, tiles, args.fps, renderer, is_running)
     finally:
         renderer.stop()