diff --git a/libraries/mbed/targets/hal/TARGET_Silicon_Labs/TARGET_EFM32/pinmap.c b/libraries/mbed/targets/hal/TARGET_Silicon_Labs/TARGET_EFM32/pinmap.c
index f1bd1dec70..a0ffce796b 100644
--- a/libraries/mbed/targets/hal/TARGET_Silicon_Labs/TARGET_EFM32/pinmap.c
+++ b/libraries/mbed/targets/hal/TARGET_Silicon_Labs/TARGET_EFM32/pinmap.c
@@ -42,7 +42,7 @@ void pin_function(PinName pin, int function)
 
 void pin_mode(PinName pin, PinMode mode)
 {
-    MBED_ASSERT(pin != NC);
+    MBED_ASSERT((0xFFFFFF00 |pin) != NC);
 
     /* Enable GPIO clock if not already done */
     if (!gpio_clock_inited) {
diff --git a/libraries/mbed/targets/hal/TARGET_Silicon_Labs/TARGET_EFM32/rtc_api.c b/libraries/mbed/targets/hal/TARGET_Silicon_Labs/TARGET_EFM32/rtc_api.c
index d02878a41d..85f73a2ccc 100644
--- a/libraries/mbed/targets/hal/TARGET_Silicon_Labs/TARGET_EFM32/rtc_api.c
+++ b/libraries/mbed/targets/hal/TARGET_Silicon_Labs/TARGET_EFM32/rtc_api.c
@@ -96,11 +96,6 @@ void rtc_init_real(uint32_t flags)
     useflags |= flags;
 
     if (!rtc_inited) {
-        /* Start LFXO and wait until it is stable */
-        CMU_OscillatorEnable(cmuOsc_LFXO, true, true);
-
-        /* Route the LFXO clock to the RTC */
-        CMU_ClockSelectSet(cmuClock_LFA, LOW_ENERGY_CLOCK_SOURCE);
         CMU_ClockEnable(cmuClock_RTC, true);
 
         /* Enable clock to the interface of the low energy modules */