diff --git a/ampel-firmware/co2_sensor.cpp b/ampel-firmware/co2_sensor.cpp
index 94d3c0f82ddf1b16e9398de5d9488baceb7022b1..6fe4ff719b326145f6aaf362be6b449652f4871e 100644
--- a/ampel-firmware/co2_sensor.cpp
+++ b/ampel-firmware/co2_sensor.cpp
@@ -18,11 +18,12 @@ namespace config {
 }
 
 #if defined(ESP8266)
-    // ???
+// ???
 #endif
 #if defined(ESP32)
 // For ESP32 : RX on GPIO17, TX on GPIO16
 #   define S8_UART_PORT  2
+#endif
 
 namespace sensor {
   HardwareSerial S8_serial(S8_UART_PORT);
@@ -70,7 +71,6 @@ namespace sensor {
     Serial.println(F("Sensor   : Senseair S8"));
     S8_serial.begin(S8_BAUDRATE);
     sensor_S8 = new S8_UART(S8_serial);
-#endif
     Serial.println();
 
     // Check if S8 is available