diff --git a/armsrc/mifaresim.c b/armsrc/mifaresim.c
index 71195aa62..81f26c5cb 100644
--- a/armsrc/mifaresim.c
+++ b/armsrc/mifaresim.c
@@ -881,8 +881,8 @@ void Mifare1ksim(uint16_t flags, uint8_t exitAfterNReads, uint8_t *datain, uint1
                         break;
                     }
                     */
-
-                    if (MifareBlockToSector(receivedCmd_dec[1]) != cardAUTHSC) {
+                    blockNo = receivedCmd_dec[1];
+                    if (MifareBlockToSector(blockNo) != cardAUTHSC) {
                         EmSend4bit(mf_crypto1_encrypt4bit(pcs, CARD_NACK_NA));
                         FpgaDisableTracing();
 
@@ -893,6 +893,7 @@ void Mifare1ksim(uint16_t flags, uint8_t exitAfterNReads, uint8_t *datain, uint1
 
                     // Compliance of MIFARE Classic EV1 1K Datasheet footnote of Table 8
                     // If access bits show that key B is Readable, any subsequent memory access will be refused.
+                    
                     if (cardAUTHKEY == AUTHKEYB && IsKeyBReadable(blockNo)) {
                         EmSend4bit(mf_crypto1_encrypt4bit(pcs, CARD_NACK_NA));
                         FpgaDisableTracing();