diff --git a/os/various/chrtclib.c b/os/various/chrtclib.c
index 6fcb3de41..9d3f4eb0c 100644
--- a/os/various/chrtclib.c
+++ b/os/various/chrtclib.c
@@ -33,6 +33,8 @@
 
 #include "chrtclib.h"
 
+#if HAL_USE_RTC || defined(__DOXYGEN__)
+
 #if (defined(STM32F4XX) || defined(STM32F2XX) || defined(STM32L1XX) ||        \
      defined(STM32F30X) || defined(STM32F37X) ||                              \
      defined(STM32F1XX) || defined(STM32F10X_MD) || defined(STM32F10X_LD) ||  \
@@ -440,4 +442,6 @@ uint32_t rtcGetTimeFatFromCounter(RTCDriver *rtcp) {
 #endif /* STM32_RTC_IS_CALENDAR  || LPC17xx_RTC_IS_CALENDAR */
 #endif /* (defined(STM32F4XX) || defined(STM32F2XX) || defined(STM32L1XX) || defined(STM32F1XX)) */
 
+#endif /* HAL_USE_RTC */
+
 /** @} */
diff --git a/os/various/chrtclib.h b/os/various/chrtclib.h
index 895abc1a7..daf53ec85 100644
--- a/os/various/chrtclib.h
+++ b/os/various/chrtclib.h
@@ -31,6 +31,8 @@
 
 #include <time.h>
 
+#if HAL_USE_RTC || defined(__DOXYGEN__)
+
 /*===========================================================================*/
 /* External declarations.                                                    */
 /*===========================================================================*/
@@ -50,6 +52,8 @@ extern "C" {
 }
 #endif
 
+#endif /* HAL_USE_RTC */
+
 #endif /* CHRTCLIB_H_ */
 
 /** @} */