diff --git a/targets/stm32l432/src/app.h b/targets/stm32l432/src/app.h
index c0353a0..5753d14 100644
--- a/targets/stm32l432/src/app.h
+++ b/targets/stm32l432/src/app.h
@@ -30,6 +30,7 @@
 // #define DISABLE_CTAPHID_WINK
 // #define DISABLE_CTAPHID_CBOR
 
+// #define ENABLE_SERIAL_PRINTING
 
 #if defined(SOLO_HACKER)
 #define SOLO_PRODUCT_NAME "Solo Hacker " SOLO_VERSION
diff --git a/targets/stm32l432/src/nfc.c b/targets/stm32l432/src/nfc.c
index 85da81a..dc66235 100644
--- a/targets/stm32l432/src/nfc.c
+++ b/targets/stm32l432/src/nfc.c
@@ -444,7 +444,7 @@ void nfc_process_iblock(uint8_t * buf, int len)
                 else
                 {
 					nfc_write_response(buf[0], SW_FILE_NOT_FOUND);
-                    printf1(TAG_NFC, "NOT selected\r\n"); dump_hex1(TAG_NFC,res, 3);
+                    printf1(TAG_NFC, "NOT selected\r\n"); dump_hex1(TAG_NFC,payload, plen);
                 }
             }
         break;
@@ -495,7 +495,7 @@ void nfc_process_iblock(uint8_t * buf, int len)
 
 
 
-            printf1(TAG_NFC,"U2F Register answered %d (took %d)\r\n", millis(), millis() - t1);
+            printf1(TAG_NFC,"U2F Register answered %d (took %d)\r\n", millis(), timestamp());
        break;
 
         case APDU_FIDO_U2F_AUTHENTICATE:
@@ -532,8 +532,7 @@ void nfc_process_iblock(uint8_t * buf, int len)
 				break;
 			}
 
-			timestamp();
-			printf1(TAG_NFC, "FIDO2 CTAP message. %d\r\n", t1);
+			printf1(TAG_NFC, "FIDO2 CTAP message. %d\r\n", timestamp());
 
 			WTX_on(WTX_TIME_DEFAULT);
             ctap_response_init(&ctap_resp);
diff --git a/targets/stm32l432/src/redirect.c b/targets/stm32l432/src/redirect.c
index f601ad8..ed4147f 100644
--- a/targets/stm32l432/src/redirect.c
+++ b/targets/stm32l432/src/redirect.c
@@ -24,7 +24,7 @@ void _putchar(char c)
 }
 
 
-int _write (int fd, const void *buf, long int len)
+int _write (int fd, const void *buf, unsigned long int len)
 {
     uint8_t * data = (uint8_t *) buf;
 #if DEBUG_LEVEL>1
@@ -43,11 +43,14 @@ int _write (int fd, const void *buf, long int len)
 	if (res == USBD_OK)
 		logbuflen = 0;
 #endif
+#ifdef ENABLE_SERIAL_PRINTING
     // Send out UART serial
     while(len--)
     {
         _putchar(*data++);
     }
+#endif
     return 0;
+
 }
 #endif