diff --git a/arch/arm/src/nrf52/nrf52_serial.c b/arch/arm/src/nrf52/nrf52_serial.c
index ab242e77a03..6d3ef94e11d 100644
--- a/arch/arm/src/nrf52/nrf52_serial.c
+++ b/arch/arm/src/nrf52/nrf52_serial.c
@@ -86,7 +86,7 @@
 #ifdef CONFIG_UART0_SERIAL_CONSOLE
 #  define CONSOLE_DEV         g_uart0port /* UART0 is console */
 #  define TTYS0_DEV           g_uart0port /* UART0 is ttyS0 */
-#elif CONFIG_UART1_SERIAL_CONSOLE
+#elif defined(CONFIG_UART1_SERIAL_CONSOLE)
 #  define CONSOLE_DEV         g_uart1port /* UART1 is console */
 #  define TTYS0_DEV           g_uart1port /* UART1 is ttyS0 */
 #endif
@@ -773,10 +773,9 @@ void arm_serialinit(void)
   /* Register the serial console */
 
   uart_register("/dev/console", &CONSOLE_DEV);
-#endif
-
   uart_register("/dev/ttyS0", &TTYS0_DEV);
   minor = 1;
+#endif
 
   /* Register all remaining UARTs */
 
@@ -786,7 +785,7 @@ void arm_serialinit(void)
     {
       /* Don't create a device for non-configured ports. */
 
-      if (g_uart_devs[i] == 0)
+      if (g_uart_devs[i] == NULL)
         {
           continue;
         }
diff --git a/arch/arm/src/nrf53/nrf53_serial.c b/arch/arm/src/nrf53/nrf53_serial.c
index d9b41e63cc3..8487e75d978 100644
--- a/arch/arm/src/nrf53/nrf53_serial.c
+++ b/arch/arm/src/nrf53/nrf53_serial.c
@@ -86,7 +86,7 @@
 #ifdef CONFIG_UART0_SERIAL_CONSOLE
 #  define CONSOLE_DEV         g_uart0port /* UART0 is console */
 #  define TTYS0_DEV           g_uart0port /* UART0 is ttyS0 */
-#elif CONFIG_UART1_SERIAL_CONSOLE
+#elif defined(CONFIG_UART1_SERIAL_CONSOLE)
 #  define CONSOLE_DEV         g_uart1port /* UART1 is console */
 #  define TTYS0_DEV           g_uart1port /* UART1 is ttyS0 */
 #endif
@@ -773,10 +773,9 @@ void arm_serialinit(void)
   /* Register the serial console */
 
   uart_register("/dev/console", &CONSOLE_DEV);
-#endif
-
   uart_register("/dev/ttyS0", &TTYS0_DEV);
   minor = 1;
+#endif
 
   /* Register all remaining UARTs */
 
@@ -786,7 +785,7 @@ void arm_serialinit(void)
     {
       /* Don't create a device for non-configured ports. */
 
-      if (g_uart_devs[i] == 0)
+      if (g_uart_devs[i] == NULL)
         {
           continue;
         }
diff --git a/arch/arm/src/nrf91/nrf91_serial.c b/arch/arm/src/nrf91/nrf91_serial.c
index 1495696d0bf..bdedf73e4a2 100644
--- a/arch/arm/src/nrf91/nrf91_serial.c
+++ b/arch/arm/src/nrf91/nrf91_serial.c
@@ -86,7 +86,7 @@
 #ifdef CONFIG_UART0_SERIAL_CONSOLE
 #  define CONSOLE_DEV         g_uart0port /* UART0 is console */
 #  define TTYS0_DEV           g_uart0port /* UART0 is ttyS0 */
-#elif CONFIG_UART1_SERIAL_CONSOLE
+#elif defined(CONFIG_UART1_SERIAL_CONSOLE)
 #  define CONSOLE_DEV         g_uart1port /* UART1 is console */
 #  define TTYS0_DEV           g_uart1port /* UART1 is ttyS0 */
 #endif
@@ -773,10 +773,9 @@ void arm_serialinit(void)
   /* Register the serial console */
 
   uart_register("/dev/console", &CONSOLE_DEV);
-#endif
-
   uart_register("/dev/ttyS0", &TTYS0_DEV);
   minor = 1;
+#endif
 
   /* Register all remaining UARTs */
 
@@ -786,7 +785,7 @@ void arm_serialinit(void)
     {
       /* Don't create a device for non-configured ports. */
 
-      if (g_uart_devs[i] == 0)
+      if (g_uart_devs[i] == NULL)
         {
           continue;
         }