diff --git a/libnfc/drivers/arygon.c b/libnfc/drivers/arygon.c
index efe418e..2e2a9ee 100644
--- a/libnfc/drivers/arygon.c
+++ b/libnfc/drivers/arygon.c
@@ -88,7 +88,7 @@ static const uint8_t arygon_error_none[] = "FF000000\x0d\x0a";
 static const uint8_t arygon_error_incomplete_command[] = "FF0C0000\x0d\x0a";
 static const uint8_t arygon_error_unknown_mode[] = "FF060000\x0d\x0a";
 
-bool    arygon_reset_tama (nfc_device *pnd);
+int    arygon_reset_tama (nfc_device *pnd);
 void    arygon_firmware (nfc_device *pnd, char *str);
 
 bool
@@ -135,11 +135,11 @@ arygon_probe (nfc_connstring connstrings[], size_t connstrings_len, size_t *pszD
       DRIVER_DATA (pnd)->abort_flag = false;
 #endif
 
-      bool res = arygon_reset_tama (pnd);
+      int res = arygon_reset_tama (pnd);
       pn53x_data_free (pnd);
       nfc_device_free (pnd);
       uart_close (sp);
-      if(!res) {
+      if(res < 0) {
         continue;
       }
 
@@ -269,7 +269,7 @@ arygon_connect (const nfc_connstring connstring)
 #endif
 
   // Check communication using "Reset TAMA" command
-  if (!arygon_reset_tama(pnd)) {
+  if (arygon_reset_tama(pnd) < 0) {
     arygon_disconnect (pnd);
     return NULL;
   }
@@ -511,7 +511,7 @@ arygon_firmware (nfc_device *pnd, char *str)
   }
 }
 
-bool
+int
 arygon_reset_tama (nfc_device *pnd)
 {
   const uint8_t arygon_reset_tama_cmd[] = { DEV_ARYGON_PROTOCOL_ARYGON_ASCII, 'a', 'r' };
@@ -526,14 +526,16 @@ arygon_reset_tama (nfc_device *pnd)
   res = uart_receive (DRIVER_DATA (pnd)->port, abtRx, szRx, 0, 1000);
   if (res != 0) {
     log_put (LOG_CATEGORY, NFC_PRIORITY_TRACE, "No reply to 'reset TAMA' command.");
-    return false;
+    pnd->last_error = NFC_EIO;
+    return pnd->last_error;
   }
 
   if (0 != memcmp (abtRx, arygon_error_none, sizeof (arygon_error_none) - 1)) {
-    return false;
+    pnd->last_error = NFC_EIO;
+    return pnd->last_error;
   }
 
-  return true;
+  return NFC_SUCCESS;
 }
 
 bool 
diff --git a/libnfc/drivers/pn532_uart.c b/libnfc/drivers/pn532_uart.c
index 4f0aa43..f47aeed 100644
--- a/libnfc/drivers/pn532_uart.c
+++ b/libnfc/drivers/pn532_uart.c
@@ -295,8 +295,8 @@ pn532_uart_send (nfc_device *pnd, const uint8_t *pbtData, const size_t szData, i
   switch (CHIP_DATA(pnd)->power_mode) {
     case LOWVBAT: {
       /** PN532C106 wakeup. */
-      if (-1 == pn532_uart_wakeup(pnd)) {
-        return NFC_ECHIP;
+      if ((res = pn532_uart_wakeup(pnd)) < 0) {
+        return res;
       }
       // According to PN532 application note, C106 appendix: to go out Low Vbat mode and enter in normal mode we need to send a SAMConfiguration command
       if ((res = pn53x_SAMConfiguration (pnd, 0x01, 500)) < 0) {
@@ -305,8 +305,8 @@ pn532_uart_send (nfc_device *pnd, const uint8_t *pbtData, const size_t szData, i
     }
     break;
     case POWERDOWN: {
-      if (-1 == pn532_uart_wakeup(pnd)) {
-        return NFC_ECHIP;
+      if ((res = pn532_uart_wakeup(pnd)) < 0) {
+        return res;
       }
     }
     break;
@@ -362,8 +362,7 @@ pn532_uart_receive (nfc_device *pnd, uint8_t *pbtData, const size_t szDataLen, i
   pnd->last_error = uart_receive (DRIVER_DATA (pnd)->port, abtRxBuf, 5, abort_p, timeout);
 
   if (abort_p && (NFC_EOPABORTED == pnd->last_error)) {
-    pn532_uart_ack (pnd);
-    return pnd->last_error;
+    return pn532_uart_ack (pnd);
   }
 
   if (pnd->last_error != 0) {
@@ -473,12 +472,13 @@ pn532_uart_receive (nfc_device *pnd, uint8_t *pbtData, const size_t szDataLen, i
 int
 pn532_uart_ack (nfc_device *pnd)
 {
+  int res = 0;
   if (POWERDOWN == CHIP_DATA(pnd)->power_mode) {
-    if (-1 == pn532_uart_wakeup(pnd)) {
-      return -1;
+    if ((res = pn532_uart_wakeup(pnd)) < 0) {
+      return res;
     }
   }
-  return (uart_send (DRIVER_DATA(pnd)->port, pn53x_ack_frame, sizeof (pn53x_ack_frame),  0) < 0) ? 0 : -1;
+  return (uart_send (DRIVER_DATA(pnd)->port, pn53x_ack_frame, sizeof (pn53x_ack_frame),  0));
 }
 
 bool