diff --git a/armsrc/apps.h b/armsrc/apps.h
index 03e2025e9..55cd61b3d 100644
--- a/armsrc/apps.h
+++ b/armsrc/apps.h
@@ -165,8 +165,8 @@ void 	OnError(uint8_t reason);
 
 
 // desfire_crypto.h
-void	*mifare_cryto_preprocess_data (desfiretag_t tag, void *data, size_t *nbytes, off_t offset, int communication_settings);
-void    *mifare_cryto_postprocess_data (desfiretag_t tag, void *data, ssize_t *nbytes, int communication_settings);
+void	*mifare_cryto_preprocess_data (desfiretag_t tag, void *data, size_t *nbytes, size_t offset, int communication_settings);
+void    *mifare_cryto_postprocess_data (desfiretag_t tag, void *data, size_t *nbytes, int communication_settings);
 void    mifare_cypher_single_block (desfirekey_t  key, uint8_t *data, uint8_t *ivect, MifareCryptoDirection direction, MifareCryptoOperation operation, size_t block_size);
 void    mifare_cypher_blocks_chained (desfiretag_t tag, desfirekey_t key, uint8_t *ivect, uint8_t *data, size_t data_size, MifareCryptoDirection direction, MifareCryptoOperation operation);
 size_t  key_block_size (const desfirekey_t  key);
diff --git a/armsrc/desfire_crypto.c b/armsrc/desfire_crypto.c
index 18ed67f65..e7eceb3cc 100644
--- a/armsrc/desfire_crypto.c
+++ b/armsrc/desfire_crypto.c
@@ -161,7 +161,7 @@ size_t enciphered_data_length (const desfiretag_t tag, const size_t nbytes, int
     return padded_data_length (nbytes + crc_length, block_size);
 }
 
-void* mifare_cryto_preprocess_data (desfiretag_t tag, void *data, size_t *nbytes, off_t offset, int communication_settings) {
+void* mifare_cryto_preprocess_data (desfiretag_t tag, void *data, size_t *nbytes, size_t offset, int communication_settings) {
     uint8_t *res = data;
     uint8_t mac[4];
     size_t edl;
@@ -289,7 +289,7 @@ void* mifare_cryto_preprocess_data (desfiretag_t tag, void *data, size_t *nbytes
 
 }
 
-void* mifare_cryto_postprocess_data (desfiretag_t tag, void *data, ssize_t *nbytes, int communication_settings)
+void* mifare_cryto_postprocess_data (desfiretag_t tag, void *data, size_t *nbytes, int communication_settings)
 {
     void *res = data;
     size_t edl;