diff --git a/docs/MQTT.md b/docs/MQTT.md
index f09c3c5428..dc385853bd 100644
--- a/docs/MQTT.md
+++ b/docs/MQTT.md
@@ -220,6 +220,13 @@ To use it you must [compile your build](Compile-your-build). Add the following t
 #define SUPPORT_MQTT_EVENT
 #endif
 ```
+To default maximum MQTT message size that Tasmota can process is 256 bytes. You can increase it by redefining the following constant in `user_config_override.h`:
+```
+#ifdef RULE_MAX_MQTT_EVENTSZ
+#undef RULE_MAX_MQTT_EVENTSZ
+#endif
+#define RULE_MAX_MQTT_EVENTSZ  512
+```
 
 ### Subscribe
 Subscribes to an MQTT topic and assigns an [`Event`](Commands#event) name to it.