diff --git a/arch/arm/src/lpc17xx_40xx/lpc17_40_serial.c b/arch/arm/src/lpc17xx_40xx/lpc17_40_serial.c
index 42fe0474e2f..d3eacc535fc 100644
--- a/arch/arm/src/lpc17xx_40xx/lpc17_40_serial.c
+++ b/arch/arm/src/lpc17xx_40xx/lpc17_40_serial.c
@@ -40,6 +40,7 @@
 #include <nuttx/config.h>
 
 #include <sys/types.h>
+#include <inttypes.h>
 #include <stdint.h>
 #include <stdbool.h>
 #include <unistd.h>
@@ -1284,7 +1285,7 @@ static int up_interrupt(int irq, void *context, void *arg)
               /* Read the modem status register (MSR) to clear */
 
               status = up_serialin(priv, LPC17_40_UART_MSR_OFFSET);
-              _info("MSR: %02x\n", status);
+              _info("MSR: %02" PRIx32 "\n", status);
               break;
             }
 
@@ -1295,7 +1296,7 @@ static int up_interrupt(int irq, void *context, void *arg)
               /* Read the line status register (LSR) to clear */
 
               status = up_serialin(priv, LPC17_40_UART_LSR_OFFSET);
-              _info("LSR: %02x\n", status);
+              _info("LSR: %02" PRIx32 "\n", status);
               break;
             }
 
@@ -1303,7 +1304,7 @@ static int up_interrupt(int irq, void *context, void *arg)
 
           default:
             {
-              _err("ERROR: Unexpected IIR: %02x\n", status);
+              _err("ERROR: Unexpected IIR: %02" PRIx32 "\n", status);
               break;
             }
         }