diff --git a/jaraco/home/trap-watcher.py b/jaraco/home/trap-watcher.py
index 8eea59b..332e84b 100644
--- a/jaraco/home/trap-watcher.py
+++ b/jaraco/home/trap-watcher.py
@@ -1,7 +1,13 @@
+import sys
+
+if sys.platform != "darwin":
+    print("This app is only available on MacOS.")
+    sys.exit(1)
+    assert False  # https://github.com/python/mypy/issues/9025#issuecomment-1087270212
+
 import asyncio
 import pathlib
 import subprocess
-import sys
 
 import keyring
 import rumps
@@ -11,7 +17,6 @@
 from . import contact
 from .compat.py38 import resources
 
-
 app = typer.Typer()
 
 
diff --git a/pyproject.toml b/pyproject.toml
index 0222de2..ac5fe3a 100644
--- a/pyproject.toml
+++ b/pyproject.toml
@@ -32,7 +32,7 @@ dependencies = [
 	'importlib_resources; python_version < "3.9"',
 	"jaraco.compat>=4.1",
 	"tempora>=5.7",
-	"rumps",
+	"rumps; sys_platform == 'darwin'",
 	"typer",
 ]
 dynamic = ["version"]