diff --git a/server.py b/server.py
index 98cb13e..70da40e 100644
--- a/server.py
+++ b/server.py
@@ -38,6 +38,16 @@ OPEN_ALERT_THRESHOLDS_MINUTES = [5, 15, 30, 60, 120]
 OPEN_ALERTS_SENT_FOR_CURRENT_OPENING = []
 
 
+def controller_message(message):
+    payload = {mysecrets.CONTROLLER_KEY: message}
+    logging.info('Controller message: %s', message)
+    r = requests.post(mysecrets.CONTROLLER_URL, data=payload, timeout=10)
+    if r.status_code == 200:
+        return True
+    else:
+        logging.exception('Unable to communicate with controller! Message: ' + message)
+        return False
+
 def get_derived_state():
     """Derives the state from the prediction history."""
     state = "unknown"
@@ -188,7 +198,9 @@ async def monitor_state_transitions(app):
 
                 for threshold in OPEN_ALERT_THRESHOLDS_MINUTES:
                     if open_duration_minutes >= threshold and threshold not in OPEN_ALERTS_SENT_FOR_CURRENT_OPENING:
-                        logging.info(f"ALERT: Garage door has been open for {threshold} minutes.")
+                        msg = f"ALERT: Garage door has been open for {threshold} minutes."
+                        controller_message(msg)
+                        logging.info(msg)
                         OPEN_ALERTS_SENT_FOR_CURRENT_OPENING.append(threshold)
             elif current_state == 'closed':
                 DOOR_OPEN_START_TIME = None