diff --git a/libfreefare/freefare_internal.h b/libfreefare/freefare_internal.h
index 0425bb5..bd1175d 100644
--- a/libfreefare/freefare_internal.h
+++ b/libfreefare/freefare_internal.h
@@ -315,14 +315,16 @@ struct mifare_ultralight_tag {
  */
 #define BUFFER_INIT(buffer_name, size) \
     uint8_t buffer_name[size]; \
+    size_t __##buffer_name##_size = size; \
     size_t __##buffer_name##_n = 0
 
 /*
  * Create a wrapper for an existing buffer.
  * BEWARE!  It eats children!
  */
-#define BUFFER_ALIAS(buffer_name, origin) \
+#define BUFFER_ALIAS(buffer_name, origin, origin_size) \
     uint8_t *buffer_name = (void *)origin; \
+    size_t __##buffer_name##_size = origin_size; \
     size_t __##buffer_name##_n = 0;
 
 #define BUFFER_SIZE(buffer_name) (__##buffer_name##_n)
diff --git a/libfreefare/mifare_classic.c b/libfreefare/mifare_classic.c
index afcf54a..3cfb367 100644
--- a/libfreefare/mifare_classic.c
+++ b/libfreefare/mifare_classic.c
@@ -89,12 +89,14 @@
     do { \
 	errno = 0; \
 	DEBUG_XFER (msg, __##msg##_n, "===> "); \
-	if ((nfc_initiator_transceive_bytes (tag->device, msg, __##msg##_n, res, &__##res##_n, 0) < 0)) { \
+	int _res; \
+	if ((_res = nfc_initiator_transceive_bytes (tag->device, msg, __##msg##_n, res, __##res##_size, 0)) < 0) { \
 	    if (disconnect) { \
 		tag->active = false; \
 	    } \
 	    return errno = EIO, -1; \
 	} \
+	__##res##_n = _res; \
 	DEBUG_XFER (res, __##res##_n, "<=== "); \
     } while (0)
 
@@ -308,7 +310,7 @@ mifare_classic_read (MifareTag tag, const MifareClassicBlockNumber block, Mifare
     ASSERT_MIFARE_CLASSIC (tag);
 
     BUFFER_INIT (cmd, 2);
-    BUFFER_ALIAS (res, data);
+    BUFFER_ALIAS (res, data, sizeof(MifareClassicBlock));
 
     BUFFER_APPEND (cmd, MC_READ);
     BUFFER_APPEND (cmd, block);
diff --git a/libfreefare/mifare_desfire.c b/libfreefare/mifare_desfire.c
index 119838c..cb812ea 100644
--- a/libfreefare/mifare_desfire.c
+++ b/libfreefare/mifare_desfire.c
@@ -172,9 +172,11 @@ static ssize_t	 read_data (MifareTag tag, uint8_t command, uint8_t file_no, off_
 	MIFARE_DESFIRE (tag)->last_picc_error = OPERATION_OK; \
 	MIFARE_DESFIRE (tag)->last_pcd_error = OPERATION_OK; \
 	DEBUG_XFER (__msg, __len, "===> "); \
-	if ((nfc_initiator_transceive_bytes (tag->device, __msg, __len, __res, &__##res##_n, 0)) < 0) { \
+	int _res; \
+	if ((_res = nfc_initiator_transceive_bytes (tag->device, __msg, __len, __res, __##res##_size, 0)) < 0) { \
 	    return errno = EIO, -1; \
 	} \
+	__##res##_n = _res; \
 	DEBUG_XFER (__res, __##res##_n, "<=== "); \
 	res[__##res##_n-2] = __res[__##res##_n-1]; \
 	__##res##_n--; \
diff --git a/libfreefare/mifare_ultralight.c b/libfreefare/mifare_ultralight.c
index 963a3f1..63304db 100644
--- a/libfreefare/mifare_ultralight.c
+++ b/libfreefare/mifare_ultralight.c
@@ -62,9 +62,11 @@
     do { \
 	errno = 0; \
 	DEBUG_XFER (msg, __##msg##_n, "===> "); \
-	if ((nfc_initiator_transceive_bytes (tag->device, msg, __##msg##_n, res, &__##res##_n, 0)) < 0) { \
+	int _res; \
+	if ((_res = nfc_initiator_transceive_bytes (tag->device, msg, __##msg##_n, res, __##res##_size, 0)) < 0) { \
 	    return errno = EIO, -1; \
 	} \
+	__##res##_n = _res; \
 	DEBUG_XFER (res, __##res##_n, "<=== "); \
     } while (0)
 
@@ -76,10 +78,12 @@
 	    return -1; \
 	} \
 	DEBUG_XFER (msg, __##msg##_n, "===> "); \
-	if ((nfc_initiator_transceive_bytes (tag->device, msg, __##msg##_n, res, &__##res##_n, 0)) < 0) { \
+	int _res; \
+	if ((_res = nfc_initiator_transceive_bytes (tag->device, msg, __##msg##_n, res, __##res##_size, 0)) < 0) { \
 	    nfc_device_set_property_bool (tag->device, NP_EASY_FRAMING, true); \
 	    return errno = EIO, -1; \
 	} \
+	__##res##_n = _res; \
 	DEBUG_XFER (res, __##res##_n, "<=== "); \
 	if (nfc_device_set_property_bool (tag->device, NP_EASY_FRAMING, true) < 0) { \
 	    errno = EIO; \
@@ -183,7 +187,7 @@ mifare_ultralight_read (MifareTag tag, MifareUltralightPageNumber page, MifareUl
 
     if (!MIFARE_ULTRALIGHT(tag)->cached_pages[page]) {
 	BUFFER_INIT (cmd, 2);
-	BUFFER_ALIAS (res, MIFARE_ULTRALIGHT(tag)->cache[page]);
+	BUFFER_ALIAS (res, MIFARE_ULTRALIGHT(tag)->cache[page], sizeof(MifareUltralightPage));
 
 	BUFFER_APPEND (cmd, 0x30);
 	BUFFER_APPEND (cmd, page);
@@ -322,8 +326,7 @@ is_mifare_ultralightc_on_reader (nfc_device *device, nfc_iso14443a_info nai)
     };
     nfc_initiator_select_passive_target (device, modulation, nai.abtUid, nai.szUidLen, &pnti);
     nfc_device_set_property_bool (device, NP_EASY_FRAMING, false);
-    size_t n;
-    ret = nfc_initiator_transceive_bytes (device, cmd_step1, sizeof (cmd_step1), res_step1, &n, 0);
+    ret = nfc_initiator_transceive_bytes (device, cmd_step1, sizeof (cmd_step1), res_step1, sizeof(res_step1), 0);
     nfc_device_set_property_bool (device, NP_EASY_FRAMING, true);
     nfc_initiator_deselect_target (device);
     return ret >= 0;