diff --git a/cap1xxx/__init__.py b/cap1xxx/__init__.py
index dab1496..d7b942b 100644
--- a/cap1xxx/__init__.py
+++ b/cap1xxx/__init__.py
@@ -494,6 +494,7 @@ def _poll(self):
         a loop, preferably threaded."""
         if self.wait_for_interrupt():
             self._handle_alert()
+        return True
 
     def _trigger_handler(self, channel, event):
         if event == "none":