diff --git a/libnfc/chips/pn53x.c b/libnfc/chips/pn53x.c
index db7f741..34cf4ad 100644
--- a/libnfc/chips/pn53x.c
+++ b/libnfc/chips/pn53x.c
@@ -371,7 +371,6 @@ int
 pn53x_wrap_frame(const uint8_t *pbtTx, const size_t szTxBits, const uint8_t *pbtTxPar,
                  uint8_t *pbtFrame)
 {
-  uint8_t  btFrame;
   uint8_t  btData;
   uint32_t uiBitPos;
   uint32_t uiDataPos = 0;
@@ -398,7 +397,7 @@ pn53x_wrap_frame(const uint8_t *pbtTx, const size_t szTxBits, const uint8_t *pbt
   // air-bytes = mirror(buffer-byte) + mirror(buffer-byte) + mirror(buffer-byte) + ..
   while (true) {
     // Reset the temporary frame byte;
-    btFrame = 0;
+    uint8_t  btFrame = 0;
 
     for (uiBitPos = 0; uiBitPos < 8; uiBitPos++) {
       // Copy as much data that fits in the frame byte
@@ -1466,9 +1465,8 @@ static void __pn53x_init_timer(struct nfc_device *pnd, const uint32_t max_cycles
 
 static uint32_t __pn53x_get_timer(struct nfc_device *pnd, const uint8_t last_cmd_byte)
 {
-  uint8_t parity;
   uint8_t counter_hi, counter_lo;
-  uint16_t counter, u16cycles;
+  uint16_t counter;
   uint32_t u32cycles;
   size_t off = 0;
   if (CHIP_DATA(pnd)->type == PN533) {
@@ -1496,6 +1494,8 @@ static uint32_t __pn53x_get_timer(struct nfc_device *pnd, const uint8_t last_cmd
     // counter saturated
     u32cycles = 0xFFFFFFFF;
   } else {
+    uint8_t parity;
+    uint16_t u16cycles;
     u16cycles = 0xFFFF - counter;
     u32cycles = u16cycles;
     u32cycles *= (CHIP_DATA(pnd)->timer_prescaler * 2 + 1);
diff --git a/libnfc/drivers/acr122_pcsc.c b/libnfc/drivers/acr122_pcsc.c
index 93af3aa..1875166 100644
--- a/libnfc/drivers/acr122_pcsc.c
+++ b/libnfc/drivers/acr122_pcsc.c
@@ -400,15 +400,14 @@ acr122_pcsc_receive(nfc_device *pnd, uint8_t *pbtData, const size_t szData, int
 {
   // FIXME: timeout is not handled
   (void) timeout;
-
   int len;
-  uint8_t  abtRxCmd[5] = { 0xFF, 0xC0, 0x00, 0x00 };
 
   if (DRIVER_DATA(pnd)->ioCard.dwProtocol == SCARD_PROTOCOL_T0) {
     /*
      * Retrieve the PN532 response.
      */
     DWORD dwRxLen = sizeof(DRIVER_DATA(pnd)->abtRx);
+    uint8_t  abtRxCmd[5] = { 0xFF, 0xC0, 0x00, 0x00 };
     abtRxCmd[4] = DRIVER_DATA(pnd)->abtRx[1];
     if (SCardTransmit(DRIVER_DATA(pnd)->hCard, &(DRIVER_DATA(pnd)->ioCard), abtRxCmd, sizeof(abtRxCmd), NULL, DRIVER_DATA(pnd)->abtRx, &dwRxLen) != SCARD_S_SUCCESS) {
       pnd->last_error = NFC_EIO;
diff --git a/libnfc/iso14443-subr.c b/libnfc/iso14443-subr.c
index 27a1ba7..0f5b2e6 100644
--- a/libnfc/iso14443-subr.c
+++ b/libnfc/iso14443-subr.c
@@ -47,10 +47,10 @@
 void
 iso14443a_crc(uint8_t *pbtData, size_t szLen, uint8_t *pbtCrc)
 {
-  uint8_t  bt;
   uint32_t wCrc = 0x6363;
 
   do {
+    uint8_t  bt;
     bt = *pbtData++;
     bt = (bt ^ (uint8_t)(wCrc & 0x00FF));
     bt = (bt ^ (bt << 4));
@@ -78,10 +78,10 @@ iso14443a_crc_append(uint8_t *pbtData, size_t szLen)
 void
 iso14443b_crc(uint8_t *pbtData, size_t szLen, uint8_t *pbtCrc)
 {
-  uint8_t  bt;
   uint32_t wCrc = 0xFFFF;
 
   do {
+    uint8_t  bt;
     bt = *pbtData++;
     bt = (bt ^ (uint8_t)(wCrc & 0x00FF));
     bt = (bt ^ (bt << 4));
diff --git a/utils/nfc-mfclassic.c b/utils/nfc-mfclassic.c
index 2e03e3f..55c2bfe 100644
--- a/utils/nfc-mfclassic.c
+++ b/utils/nfc-mfclassic.c
@@ -184,7 +184,6 @@ static  bool
 authenticate(uint32_t uiBlock)
 {
   mifare_cmd mc;
-  uint32_t uiTrailerBlock;
 
   // Set the authentication information (uid)
   memcpy(mp.mpa.abtAuthUid, nt.nti.nai.abtUid + nt.nti.nai.szUidLen - 4, 4);
@@ -196,6 +195,7 @@ authenticate(uint32_t uiBlock)
   if (bUseKeyFile) {
 
     // Locate the trailer (with the keys) used for this sector
+    uint32_t uiTrailerBlock;
     uiTrailerBlock = get_trailer_block(uiBlock);
 
     // Extract the right key from dump file