diff --git a/src/cmdhfmfhard.c b/src/cmdhfmfhard.c
index 4a3597f..647eee3 100644
--- a/src/cmdhfmfhard.c
+++ b/src/cmdhfmfhard.c
@@ -1289,8 +1289,8 @@ static int acquire_nonces(uint8_t blockNo, uint8_t keyType, uint8_t *key, uint8_
     num_acquired_nonces = 0;
 
 
-    int e_sector = blockNo / 4;
-    int a_sector = trgBlockNo / 4;
+    int e_sector = block_to_sector(blockNo);
+    int a_sector = block_to_sector(trgBlockNo);
     pKeys pk = {NULL, 0};
     bool dumpKeysA = (trgKeyType == MC_AUTH_A ? true : false);
     //            
diff --git a/src/mfoc.c b/src/mfoc.c
index 35d23d8..335936f 100644
--- a/src/mfoc.c
+++ b/src/mfoc.c
@@ -1028,7 +1028,7 @@ int mf_enhanced_auth(int e_sector, int a_sector, mftag t, mfreader r, denonce *d
   // Prepare AUTH command
   Auth[0] = (t.sectors[e_sector].foundKeyA) ? MC_AUTH_A : MC_AUTH_B;
   if (mode == 'h') {
-    Auth[1] = e_sector * 4; //block
+    Auth[1] = sector_to_block(e_sector); //block
   }
   iso14443a_crc_append(Auth, 2);
   // fprintf(stdout, "\nAuth command:\t");