diff --git a/mqtt/include/mqtt.h b/mqtt/include/mqtt.h
index b855c03..862c481 100644
--- a/mqtt/include/mqtt.h
+++ b/mqtt/include/mqtt.h
@@ -140,7 +140,7 @@ void ICACHE_FLASH_ATTR MQTT_OnPublished(MQTT_Client *mqttClient, MqttCallback pu
 void ICACHE_FLASH_ATTR MQTT_OnTimeout(MQTT_Client *mqttClient, MqttCallback timeoutCb);
 void ICACHE_FLASH_ATTR MQTT_OnData(MQTT_Client *mqttClient, MqttDataCallback dataCb);
 BOOL ICACHE_FLASH_ATTR MQTT_Subscribe(MQTT_Client *client, char* topic, uint8_t qos);
-BOOL MQTT_UnSubscribe(MQTT_Client *client, char* topic);
+BOOL ICACHE_FLASH_ATTR MQTT_UnSubscribe(MQTT_Client *client, char* topic);
 void ICACHE_FLASH_ATTR MQTT_Connect(MQTT_Client *mqttClient);
 void ICACHE_FLASH_ATTR MQTT_Disconnect(MQTT_Client *mqttClient);
 BOOL ICACHE_FLASH_ATTR MQTT_Publish(MQTT_Client *client, const char* topic, const char* data, int data_length, int qos, int retain);