diff --git a/src/allmydata/watchdog/_watchdog_541.py b/src/allmydata/watchdog/_watchdog_541.py
new file mode 100644
index 000000000..87686ce6d
--- /dev/null
+++ b/src/allmydata/watchdog/_watchdog_541.py
@@ -0,0 +1,16 @@
+"""
+Hotfix for https://github.com/gorakhargosh/watchdog/issues/541
+"""
+
+from watchdog.observers.fsevents import FSEventsEmitter
+
+# The class object has already been bundled up in the default arguments to
+# FSEventsObserver.__init__.  So mutate the class object (instead of replacing
+# it with a safer version).
+original_on_thread_stop = FSEventsEmitter.on_thread_stop
+def safe_on_thread_stop(self):
+    if self.is_alive():
+        return original_on_thread_stop(self)
+
+def patch():
+    FSEventsEmitter.on_thread_stop = safe_on_thread_stop
diff --git a/src/allmydata/watchdog/inotify.py b/src/allmydata/watchdog/inotify.py
index 5db35d9dd..4b717aae6 100644
--- a/src/allmydata/watchdog/inotify.py
+++ b/src/allmydata/watchdog/inotify.py
@@ -53,6 +53,9 @@ from ..util.eliotutil import (
     validateInstanceOf,
 )
 
+import ._watchdog_541
+_watchdog_541.patch()
+
 NOT_STARTED = "NOT_STARTED"
 STARTED     = "STARTED"
 STOPPING    = "STOPPING"