diff --git a/src/RTCZero.cpp b/src/RTCZero.cpp
index 71bfd8d..7a97dd1 100644
--- a/src/RTCZero.cpp
+++ b/src/RTCZero.cpp
@@ -39,7 +39,7 @@ RTCZero::RTCZero()
   _configured = false;
 }
 
-void RTCZero::begin(bool resetTime)
+void RTCZero::begin(bool twelveHrsformat,bool resetTime)
 {
   uint16_t tmp_reg = 0;
   
@@ -72,6 +72,10 @@ void RTCZero::begin(bool resetTime)
   
   //According to the datasheet RTC_MODE2_CTRL_CLKREP = 0 for 24h
   tmp_reg &= ~RTC_MODE2_CTRL_CLKREP; // 24h time representation
+  if(twelveHrsformat)
+  {
+    tmp_reg |= RTC_MODE2_CTRL_CLKREP; // 12h time representation 
+  }
 
   RTC->MODE2.READREQ.reg &= ~RTC_READREQ_RCONT; // disable continuously mode
 
diff --git a/src/RTCZero.h b/src/RTCZero.h
index f74f091..73fa796 100644
--- a/src/RTCZero.h
+++ b/src/RTCZero.h
@@ -39,7 +39,7 @@ class RTCZero {
   };
 
   RTCZero();
-  void begin(bool resetTime = false);
+  void begin(bool twelveHrsformat = false,bool resetTime = false);
 
   void enableAlarm(Alarm_Match match);
   void disableAlarm();