diff --git a/libnfc/drivers/pn532_uart.c b/libnfc/drivers/pn532_uart.c
index 4e68eaa..8b69c12 100644
--- a/libnfc/drivers/pn532_uart.c
+++ b/libnfc/drivers/pn532_uart.c
@@ -154,6 +154,8 @@ pn532_uart_connect (const nfc_device_desc_t * pndd)
 
   uart_set_speed (sp, pndd->uiSpeed);
 
+  // Send ACK frame to cancel a previous command
+  pn532_uart_ack ((nfc_device_spec_t) sp);
   // PN532 could be powered down, we need to wake it up before line testing.
   pn532_uart_wakeup ((nfc_device_spec_t) sp);
   // Check communication using "Diagnose" command, with "Comunication test" (0x00)