diff --git a/src/machine/machine_nrf.go b/src/machine/machine_nrf.go
index d0a1a913..34bd78b2 100644
--- a/src/machine/machine_nrf.go
+++ b/src/machine/machine_nrf.go
@@ -78,6 +78,7 @@ func (uart UART) Configure(config UARTConfig) {
 	nrf.UART0.INTENSET = nrf.UART_INTENSET_RXDRDY_Msk
 
 	// Enable RX IRQ.
+	arm.SetPriority(nrf.IRQ_UART0, 0xc0) // low priority
 	arm.EnableIRQ(nrf.IRQ_UART0)
 }
 
diff --git a/src/runtime/runtime_nrf.go b/src/runtime/runtime_nrf.go
index b914159b..41524ae0 100644
--- a/src/runtime/runtime_nrf.go
+++ b/src/runtime/runtime_nrf.go
@@ -42,7 +42,7 @@ func initLFCLK() {
 
 func initRTC() {
 	nrf.RTC1.TASKS_START = 1
-	// TODO: set priority
+	arm.SetPriority(nrf.IRQ_RTC1, 0xc0) // low priority
 	arm.EnableIRQ(nrf.IRQ_RTC1)
 }