diff --git a/client/src/mifare/desfirecrypto.c b/client/src/mifare/desfirecrypto.c
index 8960b8b96..f6e316096 100644
--- a/client/src/mifare/desfirecrypto.c
+++ b/client/src/mifare/desfirecrypto.c
@@ -189,9 +189,9 @@ void DesfireCryptoEncDecEx(DesfireContext *ctx, bool use_session_key, uint8_t *s
     size_t offset = 0;
     while (offset < srcdatalen) {
         if (use_session_key)
-            DesfireCryptoEncDecSingleBlock(ctx->sessionKeyMAC, ctx->keyType, srcdata + offset, data, xiv, encode, encode);
+            DesfireCryptoEncDecSingleBlock(ctx->sessionKeyMAC, ctx->keyType, srcdata + offset, data + offset, xiv, encode, encode);
         else
-            DesfireCryptoEncDecSingleBlock(ctx->key, ctx->keyType, srcdata + offset, data, xiv, encode, encode);
+            DesfireCryptoEncDecSingleBlock(ctx->key, ctx->keyType, srcdata + offset, data + offset, xiv, encode, encode);
         offset += block_size;
     }