diff --git a/lib/nfc/nfc_worker.c b/lib/nfc/nfc_worker.c
index c2b89c71a..ae6c504b0 100644
--- a/lib/nfc/nfc_worker.c
+++ b/lib/nfc/nfc_worker.c
@@ -741,7 +741,8 @@ void nfc_worker_mf_classic_dict_attack(NfcWorker* nfc_worker) {
                     if(mf_classic_authenticate_skip_activate(
                            &tx_rx, block_num, key, MfClassicKeyA, !deactivated, cuid)) {
                         mf_classic_set_key_found(data, i, MfClassicKeyA, key);
-                        FURI_LOG_D(TAG, "Key A found");
+                        FURI_LOG_D(
+                            TAG, "Key A found: %04lx%08lx", (uint32_t)(key >> 32), (uint32_t)key);
                         nfc_worker->callback(NfcWorkerEventFoundKeyA, nfc_worker->context);
 
                         uint64_t found_key;
@@ -763,8 +764,14 @@ void nfc_worker_mf_classic_dict_attack(NfcWorker* nfc_worker) {
                     deactivated = true;
                 } else {
                     // If the key A is marked as found and matches the searching key, invalidate it
+                    uint8_t found_key[6];
+                    memcpy(found_key, data->block[i].value, 6);
+
+                    uint8_t current_key[6];
+                    memcpy(current_key, &key, 6);
+
                     if(mf_classic_is_key_found(data, i, MfClassicKeyA) &&
-                       data->block[i].value[0] == key) {
+                       found_key == current_key) {
                         mf_classic_set_key_not_found(data, i, MfClassicKeyA);
                         is_key_a_found = false;
                         FURI_LOG_D(TAG, "Key %dA not found in attack", i);
@@ -774,7 +781,8 @@ void nfc_worker_mf_classic_dict_attack(NfcWorker* nfc_worker) {
                     is_key_b_found = mf_classic_is_key_found(data, i, MfClassicKeyB);
                     if(mf_classic_authenticate_skip_activate(
                            &tx_rx, block_num, key, MfClassicKeyB, !deactivated, cuid)) {
-                        FURI_LOG_D(TAG, "Key B found");
+                        FURI_LOG_D(
+                            TAG, "Key B found: %04lx%08lx", (uint32_t)(key >> 32), (uint32_t)key);
                         mf_classic_set_key_found(data, i, MfClassicKeyB, key);
                         nfc_worker->callback(NfcWorkerEventFoundKeyB, nfc_worker->context);
                         nfc_worker_mf_classic_key_attack(nfc_worker, key, &tx_rx, i + 1);
@@ -782,8 +790,14 @@ void nfc_worker_mf_classic_dict_attack(NfcWorker* nfc_worker) {
                     deactivated = true;
                 } else {
                     // If the key B is marked as found and matches the searching key, invalidate it
+                    uint8_t found_key[6];
+                    memcpy(found_key, data->block[i].value + 10, 6);
+
+                    uint8_t current_key[6];
+                    memcpy(current_key, &key, 6);
+
                     if(mf_classic_is_key_found(data, i, MfClassicKeyB) &&
-                       data->block[i].value[10] == key) {
+                       found_key == current_key) {
                         mf_classic_set_key_not_found(data, i, MfClassicKeyB);
                         is_key_b_found = false;
                         FURI_LOG_D(TAG, "Key %dB not found in attack", i);
diff --git a/lib/nfc/protocols/mifare_classic.c b/lib/nfc/protocols/mifare_classic.c
index d2d7467dc..204e3a5eb 100644
--- a/lib/nfc/protocols/mifare_classic.c
+++ b/lib/nfc/protocols/mifare_classic.c
@@ -892,11 +892,25 @@ bool mf_classic_emulator(MfClassicEmulator* emulator, FuriHalNfcTxRxContext* tx_
             MfClassicSectorTrailer* sector_trailer =
                 (MfClassicSectorTrailer*)emulator->data.block[sector_trailer_block].value;
             if(cmd == MF_CLASSIC_AUTH_KEY_A_CMD) {
-                key = nfc_util_bytes2num(sector_trailer->key_a, 6);
-                access_key = MfClassicKeyA;
+                if(mf_classic_is_key_found(
+                       &emulator->data, mf_classic_get_sector_by_block(block), MfClassicKeyA)) {
+                    key = nfc_util_bytes2num(sector_trailer->key_a, 6);
+                    access_key = MfClassicKeyA;
+                } else {
+                    FURI_LOG_D(TAG, "Key not known");
+                    command_processed = true;
+                    break;
+                }
             } else {
-                key = nfc_util_bytes2num(sector_trailer->key_b, 6);
-                access_key = MfClassicKeyB;
+                if(mf_classic_is_key_found(
+                       &emulator->data, mf_classic_get_sector_by_block(block), MfClassicKeyB)) {
+                    key = nfc_util_bytes2num(sector_trailer->key_b, 6);
+                    access_key = MfClassicKeyB;
+                } else {
+                    FURI_LOG_D(TAG, "Key not known");
+                    command_processed = true;
+                    break;
+                }
             }
 
             uint32_t nonce = prng_successor(DWT->CYCCNT, 32) ^ 0xAA;