diff --git a/oslo_concurrency/watchdog.py b/oslo_concurrency/watchdog.py
index 692e9ba..72b3680 100644
--- a/oslo_concurrency/watchdog.py
+++ b/oslo_concurrency/watchdog.py
@@ -67,3 +67,4 @@ def watch(logger, action, level=logging.DEBUG, after=5.0):
         yield
     finally:
         timer.cancel()
+        timer.join()