diff --git a/utils/mifare.h b/utils/mifare.h
index 4498c10..29134cf 100644
--- a/utils/mifare.h
+++ b/utils/mifare.h
@@ -87,11 +87,11 @@ bool    nfc_initiator_mifare_cmd(nfc_device *pnd, const mifare_cmd mc, const uin
 
 // MIFARE Classic
 typedef struct {
-  uint8_t  abtUID[4];
+  uint8_t  abtUID[4];  // beware for 7bytes UID it goes over next fields
   uint8_t  btBCC;
-  uint8_t  btUnknown;
+  uint8_t  btSAK;      // beware it's not always exactly SAK
   uint8_t  abtATQA[2];
-  uint8_t  abtUnknown[8];
+  uint8_t  abtManufacturer[8];
 } mifare_classic_block_manufacturer;
 
 typedef struct {