diff --git a/docs/web-install.md b/docs/web-install.md
index f078a74..d77dfd7 100644
--- a/docs/web-install.md
+++ b/docs/web-install.md
@@ -148,3 +148,11 @@ The manifest's file URL must then be `http://localhost:8000/…` or
   `frame_webinstall.dispatch()` and deletes the folder.
 - The app registers the scheme each time it starts, so the last Frame Control
   started (e.g. a development checkout) handles the links.
+
+**Quitting during a stalled download.** On macOS and Linux, quitting stops a
+download at once (`shutdown()` on its socket wakes the blocked read). On
+Windows that doesn't wake a read in another thread, and closing the handle
+under a TLS read isn't safe, so a download that has stalled holds the quit for
+the 4-second grace period until the app stops the server; the partial file is
+removed on the next start. Downloads that are still moving stop at their next
+read either way.
diff --git a/tests/test_webinstall.py b/tests/test_webinstall.py
index 53917b7..1858297 100644
--- a/tests/test_webinstall.py
+++ b/tests/test_webinstall.py
@@ -328,6 +328,10 @@ class ServerJobs(unittest.TestCase):
         self.assertEqual((job["phase"], job["message"]), ("done", "ok"))
 
     def stall_then_shutdown(self, scheme, reply):
+        if os.name == "nt":
+            # shutdown() from another thread doesn't wake a blocked recv on Windows, and
+            # closing the handle under a TLS read isn't safe; see web-install.md.
+            self.skipTest("Windows: a stalled download is only dropped when the app stops the server")
         """Start a download from a server that stalls after sending reply; shutdown must stop it quickly."""
         stall = socket.socket()
         stall.bind(("127.0.0.1", 0))