diff --git a/Src/admin_vendor.c b/Src/admin_vendor.c
index 043dc9e..2bf9714 100644
--- a/Src/admin_vendor.c
+++ b/Src/admin_vendor.c
@@ -56,6 +56,36 @@ int admin_vendor_version(const CAPDU *capdu, RAPDU *rapdu) {
   return 0;
 }
 
+int admin_vendor_nfc_enable(const CAPDU *capdu, RAPDU *rapdu) {
+  if (P1 != 0x00 && P1 != 0x01) EXCEPT(SW_WRONG_P1P2);
+  if (P2 != 0x00) EXCEPT(SW_WRONG_P1P2);
+  if (LC != 0x00) EXCEPT(SW_WRONG_LENGTH);
+
+  uint32_t magic = P1 * 0x50 + 0x100;
+  FLASH_OBProgramInitTypeDef cfg = {
+    .OptionType = OPTIONBYTE_PCROP,
+    .PCROPConfig = FLASH_BANK_1,
+    .PCROPStartAddr = FLASH_BASE + magic, // Reuse this option word as NFC switch
+    .PCROPEndAddr = FLASH_BASE + 0xF, // Fixed value
+  };
+  DBG_MSG("Unlock OB\n");
+  HAL_FLASH_Unlock();
+  HAL_FLASH_OB_Unlock();
+  int ret = HAL_FLASHEx_OBProgram(&cfg);
+  HAL_FLASH_OB_Lock();
+  HAL_FLASH_Lock();
+  HAL_FLASHEx_OBGetConfig(&cfg);
+  uint32_t *flash_loc = (uint32_t*) 0x1FFF7808U;
+  DBG_MSG("HAL_FLASHEx_OBGetConfig: %d %x %x %x\n",
+    ret, cfg.PCROPStartAddr, cfg.PCROPEndAddr, *flash_loc);
+  // DBG_MSG("value= %x %x\n", *(uint32_t*)FLASH_BASE, *(uint32_t*)cfg.PCROPStartAddr);
+
+  if (ret != HAL_OK) return -1;
+
+  return 0;
+}
+
+
 extern uint32_t _stack_boundary;
 
 static int stack_test(const CAPDU *capdu, RAPDU *rapdu) {
diff --git a/Src/main.c b/Src/main.c
index 9579593..74483e5 100644
--- a/Src/main.c
+++ b/Src/main.c
@@ -274,6 +274,15 @@ static void config_usb_mode(void) {
   // enable the device_periodic_task, which controls LED and Touch sensing
   device_loop_enable = 1;
 }
+
+static int check_is_nfc_en(void) {
+  uint32_t *flash_loc = (uint32_t*) 0x1FFF7808U;
+  uint32_t val = *flash_loc; //FLASH->PCROP1SR;
+  DBG_MSG("%x\n", val);
+  return val == 0xFFFFFFFFU || // ST production default value
+          val == 0xFFFF802a; // magic written by admin_vendor_nfc_enable()
+}
+
 // Called by core library
 void USBD_LL_Init_Done(void)
 {
@@ -316,7 +325,7 @@ int main(void) {
   MX_USART2_UART_Init();
   SetupMPU(); // comment out this line during on-chip debugging
   /* USER CODE BEGIN 2 */
-  in_nfc_mode = 1; // boot in NFC mode by default
+  in_nfc_mode = check_is_nfc_en(); // boot in NFC mode by default
   nfc_init();
   set_nfc_state(in_nfc_mode);
 
@@ -327,6 +336,10 @@ int main(void) {
   applets_install();
   init_apdu_buffer();
 
+  if (!in_nfc_mode) {
+    while (!detect_usb());
+    config_usb_mode();
+  }
   DBG_MSG("Main Loop\n");
   /* USER CODE END 2 */