diff --git a/src/handler/mhz19_co2.py b/src/handler/mhz19_co2.py
index 74c4fde..a65e95a 100644
--- a/src/handler/mhz19_co2.py
+++ b/src/handler/mhz19_co2.py
@@ -5,7 +5,7 @@ class Mhz19Co2:
     def __init__(self):
         self.last_read = None
 
-        self.serial_port = "/dev/tty.usbserial-B001BTPZ"
+        self.serial_port = "/dev/serial0"
         self.baud_rate = 9600
         self.byte_size = 8
         self.parity = "N"
@@ -18,6 +18,7 @@ class Mhz19Co2:
         return self.last_read
 
     def read(self):
+        ser = None
         try:
             ser = serial.Serial(
                 port=self.serial_port,