diff --git a/src/FabReader_v2/src/NFC.cpp b/src/FabReader_v2/src/NFC.cpp
index c1f9383..63324cd 100644
--- a/src/FabReader_v2/src/NFC.cpp
+++ b/src/FabReader_v2/src/NFC.cpp
@@ -100,6 +100,11 @@ bool NFC::testCard()
 
 MFRC522::StatusCode NFC::Transceive(byte* command, byte command_len, byte* response, byte* response_len)
 {
+    if(command_len >= 0xFF - 4)
+    {
+        return MFRC522::STATUS_NO_ROOM;
+    }
+
     MFRC522::StatusCode state;
     byte request_buffer[APDU_BUFFER_SIZE + 4]; // APDU Size + PCB + CID + 2x CRC
     byte request_buffer_size = command_len + 4;
@@ -122,8 +127,8 @@ MFRC522::StatusCode NFC::Transceive(byte* command, byte command_len, byte* respo
 		return state;
 	}
 
-    byte response_buffer[APDU_BUFFER_SIZE + 4]; // APDU Size + PCB + CID + 2x CRC
-    byte response_buffer_size;
+    byte response_buffer[APDU_BUFFER_SIZE + 4] = {0}; // APDU Size + PCB + CID + 2x CRC
+    byte response_buffer_size = 0xFF;
     
     printbytes(request_buffer, request_buffer_size);
 	state = rfid->PCD_TransceiveData(request_buffer, request_buffer_size, response_buffer, &response_buffer_size);