   // Limit the brightness somewhat (scale is 0-255)
   LEDS.setBrightness(64);
   
-  for(uint8_t i=0; i<NUM_LEDS; ++i)
+  for(uint8_t i=0; i<NUM_LEDS; ++i){
     leds[i] = CRGB::White;
+    walker_leds[i] = CRGB::White;
+  }
   
   LEDS.show();
   Serial.begin(57600);

  
  if(millis()-prevUpdateTime >= UPDATE_TIME){
    prevUpdateTime = millis();
    update();
  }
  

    // Turn off the current colour in the current 'source' led
    if(colour_counter==2){
      // moved out blue
      walker_leds[leds_index] = CRGB::Yellow;
    } else if(colour_counter==1) {
      // moved out green as well
      walker_leds[leds_index] = CRGB::Red;
    } else if(colour_counter==0){
      walker_leds[leds_index] = CRGB::Black;
    }
  }
  
  step_counter--;
  // Light up the properly-coloured led in the current position
  walker_leds[step_counter] = moving_colours[colour_counter];
}

void update(){
