diff --git a/config_definition.h b/config_definition.h
index 9e89cd6..f64eae2 100644
--- a/config_definition.h
+++ b/config_definition.h
@@ -167,6 +167,9 @@ struct gpu_cfg_custom_temp {
 	uint16_t temp_fan_max;
 } __packed;
 
+enum gpu_cfg_fan_flag {
+	GPU_CFG_FAN_FLAG_ALWAYS_ON = 0x01,
+};
 struct gpu_cfg_fan {
 	uint8_t idx;
 	uint8_t flags;