diff --git a/src/STM32RTC.cpp b/src/STM32RTC.cpp
index b95a6ea..1c0ac13 100644
--- a/src/STM32RTC.cpp
+++ b/src/STM32RTC.cpp
@@ -915,6 +915,9 @@ void STM32RTC::setY2kEpoch(uint32_t ts)
 void STM32RTC::configForLowPower(Source_Clock source)
 {
 #if defined(HAL_PWR_MODULE_ENABLED)
+#ifdef __HAL_RCC_RTCAPB_CLKAM_ENABLE
+  __HAL_RCC_RTCAPB_CLKAM_ENABLE();
+#endif
   if (!_configured) {
     _clockSource = source;
     // Enable RTC