 // The TinyGPS++ object
 TinyGPSPlus gps;
 
-int lastExecutionMillis = 0;
-int lastSendMillis = 0;
-int lastBeepMillis = 0;
+unsigned long lastExecutionMillis = 0;
+unsigned long lastSendMillis = 0;
+unsigned long lastBeepMillis = 0;
 
 
 

  }
  if(receivedBikeKillSignal()){
    Serial.println("Deactivating Bike...");
    if(currentMillis - lastBeepMillis > 1000) {
      lastBeepMillis = currentMillis;
      beep(200);
    }
  }
  led_off();

  while (available > 0){
    if (gps.encode(gpsSerial.read())){
      displayInfo();
      if (gps.location.isValid() && (lastSendMillis == 0 || currentMillis - lastSendMillis > 30000)){
        lastSendMillis = currentMillis;
        transmit_coords(gps.location.lat(), gps.location.lng());
      }
