diff --git a/STM32F1/libraries/RTClock/src/RTClock.cpp b/STM32F1/libraries/RTClock/src/RTClock.cpp
index f6907ed..8d65c1c 100755
--- a/STM32F1/libraries/RTClock/src/RTClock.cpp
+++ b/STM32F1/libraries/RTClock/src/RTClock.cpp
@@ -39,7 +39,7 @@
 	
 	}//end RTC
 
-	RTClock::RTClock(rtc_clk_src src, uint16 prescaler ) {
+	RTClock::RTClock(rtc_clk_src src, uint32 prescaler ) {
 		switch (src) {
 	
 		case RTCSEL_LSE : {
diff --git a/STM32F1/libraries/RTClock/src/RTClock.h b/STM32F1/libraries/RTClock/src/RTClock.h
index a225c94..7e758db 100755
--- a/STM32F1/libraries/RTClock/src/RTClock.h
+++ b/STM32F1/libraries/RTClock/src/RTClock.h
@@ -41,7 +41,7 @@ class RTClock {
  public:
  	RTClock();
     RTClock(rtc_clk_src src ); 
-	RTClock(rtc_clk_src src, uint16 prescaler );
+	RTClock(rtc_clk_src src, uint32 prescaler );
 	//~RTClock(); //to implement
 	
 	void breakTime(time_t epoch_time, tm_t & tmm);