diff --git a/vigilar/web/blueprints/system.py b/vigilar/web/blueprints/system.py
index 771c350..dccd603 100644
--- a/vigilar/web/blueprints/system.py
+++ b/vigilar/web/blueprints/system.py
@@ -61,6 +61,8 @@ def _publish_arm_request(cfg: VigilarConfig, payload: dict) -> None:
 
     bus = MessageBus(cfg.mqtt, client_id="vigilar-web-arm-request")
     bus.connect()
+    if not bus.connected:
+        raise RuntimeError("MQTT broker did not accept connection within timeout")
     try:
         bus.publish(Topics.SYSTEM_ARM_REQUEST, payload)
     finally: