diff --git a/os/hal/platforms/STM32/rtc_lld.h b/os/hal/platforms/STM32/rtc_lld.h
index 2ec4427d5..c2c6f676b 100644
--- a/os/hal/platforms/STM32/rtc_lld.h
+++ b/os/hal/platforms/STM32/rtc_lld.h
@@ -69,6 +69,7 @@
 
 /**
  * @brief Structure representing an RTC driver.
+ * @note  This driver if dummy when callbacks disabled.
  */
 struct RTCDriver{
 #if RTC_SUPPORTS_CALLBACKS