diff --git a/simpleclock.ino b/simpleclock.ino
index 41e980b..5cfdba5 100644
--- a/simpleclock.ino
+++ b/simpleclock.ino
@@ -49,7 +49,9 @@ volatile bool timeSkewEven = false;  // comp. 1 additional second per 2 days
 /* ambient light compensation aka night mode */
 const int photoPin = A2;
 volatile bool measureAmbLight = true;
-unsigned int ambLight = 0;
+unsigned int ambLight = 0;           // actual value
+unsigned int ambLight2 = 0;          // previous med. value
+unsigned int ambLight3 = 0;          // pre-previous med. value
 unsigned long previousLightTimer = 0;
 const long refresh_interval = 40;    // refresh rate 25Hz
 
@@ -238,6 +240,7 @@ void loop()
 	    (previousLightTimer > currentMillis)) { // millis() reset every ~49 days
 		previousLightTimer = currentMillis;
 		ambLight = analogRead(photoPin);
+		ambLight = (ambLight + ambLight2 + ambLight3) / 3;
 
 /* Ambient light compensation
  * ambLight can be in range of 0..1023, if it 910+, it has point to use
@@ -279,6 +282,9 @@ void loop()
 		} else if (ambLight < 100) {
 			Display.setBrightness(-22);
 		}
+
+		ambLight3 = ambLight2;
+		ambLight2 = ambLight;
 	}
 
 	Display.refreshDisplay();