diff --git a/custom_components/better_thermostat/calibration.py b/custom_components/better_thermostat/calibration.py
index 55a88b20..8a7bf2b8 100644
--- a/custom_components/better_thermostat/calibration.py
+++ b/custom_components/better_thermostat/calibration.py
@@ -70,9 +70,7 @@ def _convert_to_float(value):
         )
         return None
 
-    _new_trv_calibration = (
-        _cur_external_temp - _cur_trv_temp_f
-    ) + _current_trv_calibration
+    _new_trv_calibration = _cur_external_temp - _cur_trv_temp_f
 
     _calibration_mode = self.real_trvs[entity_id]["advanced"].get(
         "calibration_mode", CalibrationMode.DEFAULT