diff --git a/fido2/ctap.c b/fido2/ctap.c
index 3ccb9cb..d23f8ad 100644
--- a/fido2/ctap.c
+++ b/fido2/ctap.c
@@ -2443,6 +2443,15 @@ uint8_t ctap_is_pin_set()
  */
 void ctap_update_pin(uint8_t * pin, int len)
 {
+
+    // Remove PIN if the new PIN is either "" or 4321
+    if (len == 0 || strncmp(pin, "4321", len) == 0) {
+    	STATE.is_pin_set = 0;
+	memset(STATE.PIN_CODE_HASH, 0, sizeof(STATE.PIN_CODE_HASH));
+	authenticator_write_state(&STATE);
+	return;
+    }
+
     if (len >= NEW_PIN_ENC_MIN_SIZE || len < 4)
     {
         printf2(TAG_ERR, "Update pin fail length\n");