diff --git a/co2_sensor.cpp b/co2_sensor.cpp
index 51d1997035763169aa6a23e738e4204cfcfdc78d..86fd8b448717c5459940ecbf34311011a54eba2f 100644
--- a/co2_sensor.cpp
+++ b/co2_sensor.cpp
@@ -86,6 +86,7 @@ namespace sensor {
       stable_measurements++;
       Serial.print(F("Number of stable measurements : "));
       Serial.println(stable_measurements);
+      //NOTE: Hue could change from blue or red to green over 60 measurements.
       waiting_color = color::green;
     } else {
       stable_measurements = 0;