diff --git a/examples/11.ArduinoISP/ArduinoISP/ArduinoISP.ino b/examples/11.ArduinoISP/ArduinoISP/ArduinoISP.ino
index 43a91d3..5e906af 100644
--- a/examples/11.ArduinoISP/ArduinoISP/ArduinoISP.ino
+++ b/examples/11.ArduinoISP/ArduinoISP/ArduinoISP.ino
@@ -341,6 +341,10 @@ uint8_t spi_transaction(uint8_t a, uint8_t b, uint8_t c, uint8_t d) {
 
 void empty_reply() {
   if (CRC_EOP == getch()) {
+    // clear RX buffer. No more host data expected until after SYNC.
+    while (SERIAL.available()) {
+      SERIAL.read();
+    }
     SERIAL.print((char)STK_INSYNC);
     SERIAL.print((char)STK_OK);
   } else {