diff --git a/ampel-firmware/co2_sensor.cpp b/ampel-firmware/co2_sensor.cpp
index 05a391e7d97816626773489c8617a07fd131b793..7e0d4d62db91ae8828546989f2e8e156c9e40aa2 100644
--- a/ampel-firmware/co2_sensor.cpp
+++ b/ampel-firmware/co2_sensor.cpp
@@ -68,8 +68,7 @@ namespace sensor {
   state current_state = BOOTUP;
   void switchState(state);
   void setCO2forDebugging(int32_t fakeCo2);
-  void calibrateSensorToSpecificPPM(int32_t calibrationLevel);
-  void calibrateSensorRightNow(int32_t calibrationLevel);
+  void calibrateSensorRightNow();
   void setAutoCalibration(int32_t autoCalibration);
   void setTimer(int32_t timestep);
 
@@ -107,11 +106,8 @@ namespace sensor {
 
     sensor_console::defineIntCommand("co2", setCO2forDebugging, F("1500 (Sets co2 level, for debugging)"));
     sensor_console::defineIntCommand("timer", setTimer, F("30 (Sets measurement interval, in s)"));
-    sensor_console::defineCommand("calibrate", startCalibrationProcess, F("(Starts calibration process)"));
-    sensor_console::defineIntCommand("calibrate", calibrateSensorToSpecificPPM,
-        F("600 (Starts calibration process, to given ppm)"));
-    sensor_console::defineIntCommand("calibrate!", calibrateSensorRightNow,
-        F("600 (Calibrates right now, to given ppm)"));
+    sensor_console::defineCommand("calibrate", startCalibrationProcess, F("(Starts calibration process, to 400ppm)"));
+    sensor_console::defineCommand("calibrate!", calibrateSensorRightNow, F("600 (Calibrates right now, to given ppm)"));
     sensor_console::defineIntCommand("auto_calibrate", setAutoCalibration, F("0/1 (Disables/enables autocalibration)"));
   }
 
@@ -158,8 +154,9 @@ namespace sensor {
 
   void calibrate() {
     Serial.print(F("Calibrating S8 now..."));
-    //FIXME: Apparently, only to 400ppm, though.
+    //TODO: Apply ppm offset, e.g. +25ppm for 425ppm?
     Serial.println(F("WARNING! FORCING CALIBRATION TO 400ppm, regardless of configuration."));
+    config::co2_calibration_level = 400; //NOTE: Seems to be hard-coded in S8
     sensor_S8->manual_calibration();
     Serial.println(F(" Done!"));
     Serial.println(F("Sensor calibrated."));
@@ -318,17 +315,8 @@ namespace sensor {
     }
   }
 
-  void calibrateSensorToSpecificPPM(int32_t calibrationLevel) {
-    Serial.println(F("TODO: Implement ME!"));
-  }
-
-  void calibrateSensorRightNow(int32_t calibrationLevel) {
-    if (calibrationLevel >= 400 && calibrationLevel <= 2000) {
-      Serial.print(F("Force calibration, right now, at "));
-      config::co2_calibration_level = calibrationLevel;
-      Serial.print(config::co2_calibration_level);
-      Serial.println(F(" ppm."));
-      calibrate();
-    }
+  void calibrateSensorRightNow() {
+    Serial.println(F("Force calibration, right now!"));
+    calibrate();
   }
 }
diff --git a/ampel-firmware/web_config.cpp b/ampel-firmware/web_config.cpp
index e201438e0ae49686c715c8fa49a1cdef2b815a15..82b352e4e89b310cec40488b189a0120a2bab8ca 100644
--- a/ampel-firmware/web_config.cpp
+++ b/ampel-firmware/web_config.cpp
@@ -199,8 +199,9 @@ namespace web_config {
     co2Params.addItem(&temperatureOffsetParam);
     temperatureOffsetParam.visible = false; // Not needed for S8
     co2Params.addItem(&altitudeParam);
-    altitudeParam.visible = false; // Not needed either
+    altitudeParam.visible = false; // Not needed either for S8
     co2Params.addItem(&atmosphericCO2Param);
+    atmosphericCO2Param.visible = false; // Hard coded 400ppm for S8 :-/
     co2Params.addItem(&autoCalibrateParam);
 
     ledParams.addItem(&minBrightnessParam);