diff --git a/targets/TARGET_NORDIC/TARGET_NRF5/TARGET_MCU_NRF52832/PeripheralNames.h b/targets/TARGET_NORDIC/TARGET_NRF5/TARGET_MCU_NRF52832/PeripheralNames.h
index 0fe6da592e..a417d4cf63 100644
--- a/targets/TARGET_NORDIC/TARGET_NRF5/TARGET_MCU_NRF52832/PeripheralNames.h
+++ b/targets/TARGET_NORDIC/TARGET_NRF5/TARGET_MCU_NRF52832/PeripheralNames.h
@@ -45,8 +45,14 @@
 extern "C" {
 #endif
 
+#ifndef STDIO_UART_TX
 #define STDIO_UART_TX     TX_PIN_NUMBER
+#endif
+
+#ifndef STDIO_UART_RX
 #define STDIO_UART_RX     RX_PIN_NUMBER
+#endif
+
 #define STDIO_UART        UART_0
 
 typedef enum {
diff --git a/targets/TARGET_NORDIC/TARGET_NRF5/TARGET_MCU_NRF52840/PeripheralNames.h b/targets/TARGET_NORDIC/TARGET_NRF5/TARGET_MCU_NRF52840/PeripheralNames.h
index 87d1983478..116c1e89d9 100644
--- a/targets/TARGET_NORDIC/TARGET_NRF5/TARGET_MCU_NRF52840/PeripheralNames.h
+++ b/targets/TARGET_NORDIC/TARGET_NRF5/TARGET_MCU_NRF52840/PeripheralNames.h
@@ -45,8 +45,14 @@
 extern "C" {
 #endif
 
+#ifndef STDIO_UART_TX
 #define STDIO_UART_TX     TX_PIN_NUMBER
+#endif
+
+#ifndef STDIO_UART_RX
 #define STDIO_UART_RX     RX_PIN_NUMBER
+#endif
+
 #define STDIO_UART        UART_0
 
 typedef enum