diff --git a/ampel-firmware/config.public.h b/ampel-firmware/config.public.h
index 06987601c9004e57b6b9de3a3b5db0625f27e9d4..d328f42da1424fc69424f8ea5bb2ee302b4bdfcb 100644
--- a/ampel-firmware/config.public.h
+++ b/ampel-firmware/config.public.h
@@ -150,7 +150,7 @@
 #  define MQTT_ENCRYPTED true // Set to false for unencrypted MQTT (e.g. with port 1883).
 #  define MQTT_USER ""
 #  define MQTT_PASSWORD ""
-#  define MQTT_TOPIC_PREFIX "CO2sensors/" // ESPxxxxxx will be added to the prefix, so complete topic will be "CO2sensors/ESPxxxxxx"
+#  define MQTT_TOPIC_PREFIX "CO2sensors/" // ESPxxxxxx will be added to the prefix, so complete topic will be "CO2sensors/ESPxxxxxx". The prefix should probably end with '/'
 
 /**
  * LoRaWAN