diff --git a/libfreefare/freefare.h b/libfreefare/freefare.h
index 8ed2620..b178248 100644
--- a/libfreefare/freefare.h
+++ b/libfreefare/freefare.h
@@ -89,7 +89,7 @@ int		 mifare_classic_transfer (MifareTag tag, const MifareClassicBlockNumber blo
 int 		 mifare_classic_get_trailer_block_permission (MifareTag tag, const MifareClassicBlockNumber block, const uint16_t permission, const MifareClassicKeyType key_type);
 int		 mifare_classic_get_data_block_permission (MifareTag tag, const MifareClassicBlockNumber block, const unsigned char permission, const MifareClassicKeyType key_type);
 
-int		 mifare_classic_format_sector (MifareTag tag, const MifareClassicBlockNumber block);
+int		 mifare_classic_format_sector (MifareTag tag, const MifareSectorNumber sector);
 
 void		 mifare_classic_trailer_block (MifareClassicBlock *block, const MifareClassicKey key_a, uint8_t ab_0, uint8_t ab_1, uint8_t ab_2, uint8_t ab_tb, const uint8_t gpb, const MifareClassicKey key_b);