diff --git a/targets/TARGET_NUVOTON/TARGET_M2351/TARGET_NUMAKER_PFM_M2351/PeripheralNames.h b/targets/TARGET_NUVOTON/TARGET_M2351/TARGET_NUMAKER_PFM_M2351/PeripheralNames.h
index b9461ac64c..cc45b2a473 100644
--- a/targets/TARGET_NUVOTON/TARGET_M2351/TARGET_NUMAKER_PFM_M2351/PeripheralNames.h
+++ b/targets/TARGET_NUVOTON/TARGET_M2351/TARGET_NUMAKER_PFM_M2351/PeripheralNames.h
@@ -100,7 +100,7 @@ typedef enum {
     UART_5 = (int) NU_MODNAME(UART5_BASE, 5, 0),
 #endif    
     // NOTE: board-specific
-    STDIO_UART  = UART_3
+    STDIO_UART  = UART_0
 } UARTName;
 
 typedef enum {