diff --git a/pointlights/pointlights.ino b/pointlights/pointlights.ino
index 4b1c4a0..9dfb66e 100644
--- a/pointlights/pointlights.ino
+++ b/pointlights/pointlights.ino
@@ -8,6 +8,7 @@ unsigned long currentMillis;
 int brightness = 0; // our main variable for setting the brightness of the LED
 float velocity = 1.0; // the speed at which we change the brightness.
 int ledPin = 9; // we use pin 9 for PWM
+int p = 0; // use to keep track how often we plot
 int plotFrequency = 2; // how often we plot, every Nth time.
 
 void setup() {