diff --git a/Firmware/Chameleon-Mini/Application/MifareClassic.c b/Firmware/Chameleon-Mini/Application/MifareClassic.c
index 15faea1..fed2f4e 100644
--- a/Firmware/Chameleon-Mini/Application/MifareClassic.c
+++ b/Firmware/Chameleon-Mini/Application/MifareClassic.c
@@ -1020,12 +1020,20 @@ uint16_t MifareClassicAppProcess(uint8_t *Buffer, uint16_t BitCount) {
                 }
             } else if (Buffer[0] == CMD_WRITE) {
                 if (ISO14443ACheckCRCA(Buffer, CMD_WRITE_FRAME_SIZE)) {
-                    DetectionLogToFlash(LOG_INFO_APP_CMD_WRITE, Buffer, 2);
-                    /* Write command. Store the address and prepare for the upcoming data.
-                     * Respond with ACK. */
-                    CurrentAddress = Buffer[1];
-                    State = STATE_WRITE;
-                    Buffer[0] = ACK_VALUE ^ Crypto1Nibble();
+					//	not allow to write block 0
+					if (Buffer[1] == 0x00) {
+						State = STATE_HALT;
+						Buffer[0] = NAK_NOT_AUTHED ^ Crypto1Nibble();
+						return ACK_NAK_FRAME_SIZE;
+					} 
+					else {
+						DetectionLogToFlash(LOG_INFO_APP_CMD_WRITE, Buffer, 2);
+						/* Write command. Store the address and prepare for the upcoming data.
+						 * Respond with ACK. */
+						CurrentAddress = Buffer[1];
+						State = STATE_WRITE;
+						Buffer[0] = ACK_VALUE ^ Crypto1Nibble();
+					}
                 } else {
                     LogEntry(LOG_ERR_APP_CHECKSUM_FAIL, Buffer, 4);
                     Buffer[0] = NAK_CRC_ERROR ^ Crypto1Nibble();