diff --git a/Libraries/PeriphDrivers/Include/MAX32657/rtc.h b/Libraries/PeriphDrivers/Include/MAX32657/rtc.h
index 187e70ec41..25bab5351b 100644
--- a/Libraries/PeriphDrivers/Include/MAX32657/rtc.h
+++ b/Libraries/PeriphDrivers/Include/MAX32657/rtc.h
@@ -75,6 +75,14 @@ typedef enum {
     MXC_RTC_INT_FL_READY = MXC_F_RTC_CTRL_RDY, /**< Timer ready interrupt flag */
 } mxc_rtc_int_fl_t;
 
+/**
+ * @brief     Clock settings
+ */
+typedef enum {
+    MXC_RTC_ERTCO_CLK = 4,
+    MXC_RTC_INRO_CLK = 5,
+} mxc_rtc_clock_t;
+
 /**
  * @brief     Set Time-of-Day alarm value and enable Interrupt
  * @param     ras    20-bit value 0-0xFFFFF
@@ -90,11 +98,19 @@ int MXC_RTC_SetTimeofdayAlarm(uint32_t ras);
  */
 int MXC_RTC_SetSubsecondAlarm(uint32_t rssa);
 
+/**
+ * @brief     Set the RTC clock source
+ * @param     clk_src   Clock source to use
+ * @retval    returns Success or Fail, see \ref MXC_ERROR_CODES
+ */
+int MXC_RTC_SetClockSource(mxc_rtc_clock_t clk_src);
+
 /**
  * @brief     Start the Real Time Clock (Blocking function)
  * @retval    returns Success or Fail, see \ref MXC_ERROR_CODES
  */
 int MXC_RTC_Start(void);
+
 /**
  * @brief     Stop the Real Time Clock (Blocking function)
  * @retval    returns Success or Fail, see \ref MXC_ERROR_CODES
diff --git a/Libraries/PeriphDrivers/Source/RTC/rtc_me30.c b/Libraries/PeriphDrivers/Source/RTC/rtc_me30.c
index 313a101295..57abb5c8a8 100644
--- a/Libraries/PeriphDrivers/Source/RTC/rtc_me30.c
+++ b/Libraries/PeriphDrivers/Source/RTC/rtc_me30.c
@@ -65,6 +65,30 @@ int MXC_RTC_SetSubsecondAlarm(uint32_t rssa)
     return MXC_RTC_RevA_SetSubsecondAlarm((mxc_rtc_reva_regs_t *)MXC_RTC, rssa);
 }
 
+int MXC_RTC_SetClockSource(mxc_rtc_clock_t clk_src)
+{
+    uint8_t retval = E_NO_ERROR;
+
+    switch (clk_src) {
+        case MXC_RTC_ERTCO_CLK:
+            MXC_GCR->clkctrl |= MXC_F_GCR_CLKCTRL_ERTCO_EN;
+            MXC_MCR->ctrl &= ~MXC_F_MCR_CTRL_CLKSEL;
+            MXC_MCR->ctrl |= MXC_S_MCR_CTRL_CLKSEL_ERTCO;
+            break;
+
+        case MXC_RTC_INRO_CLK:
+            MXC_MCR->ctrl &= ~MXC_F_MCR_CTRL_CLKSEL;
+            MXC_MCR->ctrl |= MXC_S_MCR_CTRL_CLKSEL_INRO_DIV4;
+            break;
+
+        default:
+            // Invalid clock source
+            return E_BAD_PARAM;
+    }
+
+    return retval;
+}
+
 int MXC_RTC_Start(void)
 {
     return MXC_RTC_RevA_Start((mxc_rtc_reva_regs_t *)MXC_RTC);
@@ -77,8 +101,6 @@ int MXC_RTC_Stop(void)
 
 int MXC_RTC_Init(uint32_t sec, uint16_t ssec)
 {
-    MXC_GCR->clkctrl |= MXC_F_GCR_CLKCTRL_ERTCO_EN;
-
     return MXC_RTC_RevA_Init((mxc_rtc_reva_regs_t *)MXC_RTC, sec, (ssec & MXC_F_RTC_SSEC_SSEC));
 }