diff --git a/custom_components/hildebrand_glow_ihd_mqtt/sensor.py b/custom_components/hildebrand_glow_ihd_mqtt/sensor.py
index 1b9fd01..c1e52b9 100755
--- a/custom_components/hildebrand_glow_ihd_mqtt/sensor.py
+++ b/custom_components/hildebrand_glow_ihd_mqtt/sensor.py
@@ -253,8 +253,8 @@
     "unit_of_measurement": "GBP",
     "state_class": SensorStateClass.TOTAL_INCREASING,
     "icon": "mdi:cash",
-    "func": lambda js : round(js['gasmeter']['energy']['import']['price']['standingcharge'] + \
-       (js['gasmeter']['energy']['import']['day'] * js['gasmeter']['energy']['import']['price']['unitrate']), 2),
+    "func": lambda js : round((js['gasmeter']['energy']['import']['price']['standingcharge'] or 0)+ \
+       ((js['gasmeter']['energy']['import']['day'] or 0) * (js['gasmeter']['energy']['import']['price']['unitrate'] or 0)), 2),
   }
 ]