diff --git a/esphome/components/mqtt/mqtt_sensor.cpp b/esphome/components/mqtt/mqtt_sensor.cpp
index 032dd3b6c6..6c77404767 100644
--- a/esphome/components/mqtt/mqtt_sensor.cpp
+++ b/esphome/components/mqtt/mqtt_sensor.cpp
@@ -59,10 +59,11 @@ void MQTTSensorComponent::send_discovery(JsonObject root, mqtt::SendDiscoveryCon
     root[MQTT_FORCE_UPDATE] = true;
 
   if (this->sensor_->get_state_class() != STATE_CLASS_NONE) {
+    auto state_class_s = state_class_to_string(this->sensor_->get_state_class());
 #ifdef USE_STORE_LOG_STR_IN_FLASH
-    root[MQTT_STATE_CLASS] = (const __FlashStringHelper *) state_class_to_string(this->sensor_->get_state_class());
+    root[MQTT_STATE_CLASS] = (const __FlashStringHelper *) state_class_s;
 #else
-    root[MQTT_STATE_CLASS] = state_class_to_string(this->sensor_->get_state_class());
+    root[MQTT_STATE_CLASS] = LOG_STR_ARG(state_class_s);
 #endif
   }