diff --git a/magicbus/plugins/opsys.py b/magicbus/plugins/opsys.py
index 4be4ff3c..7a1c8335 100644
--- a/magicbus/plugins/opsys.py
+++ b/magicbus/plugins/opsys.py
@@ -265,8 +265,16 @@ def wait(self, timeout=None, poll_interval=0.1):
 
     def join(self, timeout=None, poll_interval=0.1):
         """Return when the PID file does not exist, or the timeout expires."""
+        try:
+            initial_stat = os.stat(self.pidfile)
+        except OSError:  # file does not exist
+            return
+
         starttime = time.time()
         while timeout is None or time.time() - starttime <= timeout:
-            if not os.path.exists(self.pidfile):
-                return
+            try:
+                if initial_stat != os.stat(self.pidfile):
+                    return  # file has been changed/replaced
+            except OSError:
+                return  # file does not exist
             time.sleep(poll_interval)
diff --git a/magicbus/test/test_signals.py b/magicbus/test/test_signals.py
index 45e54a5d..f9f9f619 100644
--- a/magicbus/test/test_signals.py
+++ b/magicbus/test/test_signals.py
@@ -57,6 +57,7 @@ def test_SIGHUP_daemonized(self):
         kill(pid, SIGHUP)
 
         # Give the server some time to restart
+        pidfile.join()
         time.sleep(1)
         for _ in range(6):
             new_pid = pidfile.wait(5)