diff --git a/custom_components/better_thermostat/events/trv.py b/custom_components/better_thermostat/events/trv.py
index 876ffe0f..5d314f2f 100644
--- a/custom_components/better_thermostat/events/trv.py
+++ b/custom_components/better_thermostat/events/trv.py
@@ -142,7 +142,7 @@ async def trigger_trv_change(self, event):
 
     _main_key = "temperature"
     if "temperature" not in old_state.attributes:
-        _main_key = "target_temp_high"
+        _main_key = "target_temp_low"
 
     _old_heating_setpoint = convert_to_float(
         str(old_state.attributes.get(_main_key, None)),