diff --git a/ampel-firmware/co2_sensor.cpp b/ampel-firmware/co2_sensor.cpp
index 74afdb38a9a0a25bfca4d387ce58b233b345326f..895e9614fa99961c0fbbf904a36706657a70041c 100644
--- a/ampel-firmware/co2_sensor.cpp
+++ b/ampel-firmware/co2_sensor.cpp
@@ -31,9 +31,8 @@ namespace sensor {
    * INITIAL -> initial state
    * BOOTUP -> state after initializing the sensor, i.e. after scd.begin()
    * READY -> sensor does output valid information (> 0 ppm) and no other condition takes place
-   * (NOTE: This state is currently unused)
-   * NEEDSCALIBRATION -> sensor measurements are too low (< 250 ppm)
-   * PREPARECALIBRATION -> forced calibration was initiated, waiting for stable measurements
+   * NEEDS_CALIBRATION -> sensor measurements are too low (< 250 ppm)
+   * PREPARE_CALIBRATION -> forced calibration was initiated, waiting for stable measurements
    * CALIBRATION -> the sensor does calibrate itself
    */
   enum state {
@@ -216,12 +215,10 @@ namespace sensor {
     case PREPARE_CALIBRATION_STABLE:
       led_effects::showWaitingLED(color::green);
       break;
-      // No special signaling here, too.
-    case CALIBRATION:
+    case CALIBRATION: // Nothing to do, will restart soon.
       break;
-      // This should not happen.
     default:
-      Serial.println(F("Encountered unknown sensor state"));
+      Serial.println(F("Encountered unknown sensor state")); // This should not happen.
     }
   }