diff --git a/source/developers/development_events.markdown b/source/developers/development_events.markdown
index 2c80e54d7ef..e078396fd05 100644
--- a/source/developers/development_events.markdown
+++ b/source/developers/development_events.markdown
@@ -46,6 +46,7 @@ def setup(hass, config):
 
     # Listener to handle fired events
     def handle_event(event):
+        nonlocal count
         count += 1
         print('Total events received:', count)